                UNITED STATES COURT OF APPEALS
                    FOR THE FIRST CIRCUIT
                                         

No. 93-2276

              AMERICAN AUTOMOBILE MANUFACTURERS 
                     ASSOCIATION, ET AL.,

                   Plaintiffs, Appellants,

                              v.

           COMMISSIONER, MASSACHUSETTS DEPARTMENT 
             OF ENVIRONMENTAL PROTECTION, ET AL.,

                    Defendants, Appellees.
                                         

         APPEAL FROM THE UNITED STATES DISTRICT COURT

              FOR THE DISTRICT OF MASSACHUSETTS

     [Hon. A. David Mazzone, Senior U.S. District Judge]
                                                       

                                         

                            Before

                     Selya, Circuit Judge,
                                         
                Bownes, Senior Circuit Judge,
                                            
                   and Cyr, Circuit Judge.
                                         

                                         

Edward  W. Warren,  with  whom  Daniel F.  Attridge,  Stuart  A.C.
                                                                  
Drake, Gary E. Marchant,  Kirkland &amp; Ellis, Robert F.  Sylvia, Eric F.
                                                                  
Eisenberg,  Hinckley,  Allen  &amp;  Snyder,  Phillip  D.  Brady, V.  Mark
                                                                  
Slywynsky, Of Counsel, American Automobile  Manufacturers Association,
     
Charles H. Lockwood, and  John T. Whatley, Of Counsel,  Association of
                                     
International  Automobile  Manufacturers,  Inc.,  were  on  brief  for
appellants.
James  R.  Milkey,  Assistant   Attorney  General,  Deputy  Chief,
                 
Environmental  Protection  Division,   with  whom  Scott  Harshbarger,
                                                                 
Attorney General  of the Commonwealth  of Massachusetts, and  David G.
                                                                  
Bookbinder,  Assistant Attorney  General, were  on brief  for appellee
      
Commissioner, Massachusetts Department of Environmental Protection.
William  H. Lewis,  Jr.,  Hunter  L.  Prillaman, Morgan,  Lewis  &amp;
                                                                  
Bockius,  Paul F. Ware, Jr.,  Michael J. Meagher,  Scott L. Robertson,
                                                                 

Goodwin,  Procter &amp;  Hoar, G.  William Frick,  and David  T. Deal,  Of
                                                             
Counsel, American  Petroleum Institute on brief  for appellee American
Petroleum
Institute.
Lois  J. Schiffer,  Acting Assistant  Attorney General,  David  C.
                                                                  
Shilton,  Timothy  J.  Dowling,  Attorneys,  Environment  and  Natural
                          
Resources Division,  Jean C. Nelson, General Counsel,  Alan W. Eckert,
                                                                 
Associate General  Counsel, and Michael J.  Horowitz, Attorney, Office
                                                
of General Counsel, United  States Environmental Protection Agency, on
brief for the United States, amicus curiae.
Jacqueline  M.  Warren,  and  Berle,  Kass  &amp;  Case  on  brief for
                                                   
American  Lung Association,  Natural  Resources  Defense Council,  and
Conservation Law Foundation, amici curiae.
G.  Oliver Koppel,  Attorney General  of  the  State of  New York,
                 
Peter  H.  Schiff,  Deputy   Solicitor,  Val  Washington,  Joan  Leary
                                                                  
Matthews, Helene G.  Goldberger, Assistant Attorneys General;  Michael
                                                                  
E.  Carpenter, Attorney General of  the State of  Maine, Sarah Roberts
                                                                  
Walton,  Assistant  Attorney  General;  Jeffrey  L. Amestoy,  Attorney
                                                       
General  of the  State  of Vermont,  J.  Wallace Malley,  Jr.,  Deputy
                                                         
Attorney  General; Jeffrey B. Pine,  Attorney General of  the State of
                              
Rhode  Island,  and  Michael  Rubin, Assistant  Attorney  General  and
                               
Environmental  Advocate, on brief for  the States of  New York, Maine,
Vermont, and Rhode Island, amici curiae.

                                         
                        August 3, 1994

                                         

          BOWNES,   Senior   Circuit   Judge.     Plaintiffs-
          BOWNES,   Senior   Circuit   Judge.
                                            

appellants,  the  Massachusetts   State  Automobile   Dealers

Association,  Inc.   and  two  trade   groups  of  automobile

manufacturers, appeal from an order denying their request for

a  preliminary  injunction.   Plaintiffs  seek  to stall  the

implementation   of   motor   vehicle    tailpipe   emissions

regulations adopted by  defendant-appellee, the  Commissioner

of  the Massachusetts Department  of Environmental Protection

(DEP).    See  Mass.  Regs.  Code  tit.  310,      7.40-7.60.
             

Defendant-appellee,   the   American   Petroleum   Institute,

intervened in support of the regulations.  

          Prior to oral argument, plaintiffs moved to dismiss

their appeal  as to all issues  but one:   whether DEP's 1995

model year requirements should be  enjoined.  DEP opposes the

motion  for  partial   dismissal  and   requests  costs   and

attorney's fees.   We grant the motion for partial dismissal.

We award DEP costs, but not attorney's fees.  With respect to

the 1995 model year  requirements, the order of the  district

court is affirmed.            I.
                              I.

                          BACKGROUND
                                    

A.        Cars and the Clean Air Act
                                    

          The  exhaust  from a  gasoline-powered engine  is a

source  of air pollution.   Motor Vehicle Mfrs.  Ass'n v. New
                                                             

York  Dep't of Envtl. Conservation, 17 F.3d 521, 524 (2d Cir.
                                  

1994) (hereinafter  MVMA).    Emissions  from  car  tailpipes
                        

                             -3-
                              3

include  hydrocarbons and nitrogen oxides (NOx), constituents

of ground-level ozone,  a major  component of smog.   Id.  at
                                                         

526.  

          The  Clean  Air  Act  is  the  federal  legislation

governing  tailpipe emissions.   The  Act directs  the United

States  Environmental Protection  Agency  (EPA) to  establish

national ambient air quality standards (NAAQS) for pollutants

such  as  ground-level  ozone.   Under  the  Act,  states are

responsible for  developing and enforcing a  plan, subject to

EPA  approval, for  attaining  and maintaining  the NAAQS  by

regulating  sources of air  pollution.  42  U.S.C.   7410(a).

States failing  to meet  the NAAQS risk  sanctions, including

the  loss of  federal highway funds.   Id.    7509.   EPA has
                                          

designated the  entire state of Massachusetts  as a "serious"

nonattainment area for  the ozone  NAAQS.  See  56 Fed.  Reg.
                                              

56,694, 56,776 (Nov. 6, 1991).

          Mobile sources  of air  pollution such as  cars and

trucks are subject to EPA regulation under    202 and 207  of

the  Act, 42 U.S.C.     7521, 7541.   EPA emissions standards

for hydrocarbons and nitrogen oxides apply to a given vehicle

based on its weight, use classification, and model year.  See
                                                             

id.    7521, 7541; MVMA, 17 F.3d at 525-26.   
                       

          State  regulation  of  motor  vehicle  emissions is

generally  preempted  by  the  Clean  Air  Act,  42 U.S.C.   

7543(a), with one  exception:  California can enforce its own

                             -4-
                              4

standards, subject to EPA approval by way of a waiver under  

209(b)  of the Act,  id.   7543(b)  (the waiver requirement).
                        

Consequently, there can  be only two types  of cars "created"

under  emissions regulations  in this country:   "California"

cars  and "federal" (that is, EPA-regulated) cars.  See id.  
                                                           

7507.  Other states  cannot take any action that  would force

manufacturers  to create a "third  vehicle."1  Id. (the third
                                                  

vehicle requirement). 

          Section 177 of the Act allows other states to adopt

standards  "identical"  to  California's   (the  identicality

requirement),  but only  if there  is  a two-year  time lapse

between  the time  the standards  are adopted  and the  first

model  year   affected  by  those  standards   (the  leadtime

requirement).   Id.  Similarly,    211 of  the Act authorizes
                   

EPA to regulate motor fuels and preempts any unapproved state

                    

1.  The third vehicle provision states: 
          Nothing in  this section  . . .  shall be
          construed  as authorizing any . . . State
          to   prohibit   or  limit,   directly  or
          indirectly, the manufacture  or sale of a
          new motor vehicle or motor vehicle engine
          that  is  certified   in  California   as
          meeting California standards, or  to take
          any action of any kind to create, or have
          the effect of  creating, a motor  vehicle
          or motor vehicle  engine different than a
          motor  vehicle  or  engine  certified  in
          California under  California standards (a
          "third vehicle") or otherwise create such
          a "third vehicle." 
42 U.S.C.   7507. 

                             -5-
                              5

regulations,  except  for California,  which  may  enact fuel

standards without EPA approval.  Id.   7545(c)(4)(B).   
                                    

                             -6-
                              6

B.        DEP's Adoption of California LEV Regulations
                                                      

          In  September 1991, California  enacted a novel set

of vehicle emissions and  clean fuels requirements called the

"Low Emissions Vehicles/Clean  Fuels" (LEV/CF) program.   The

LEV component  of the program  requires the creation  of four

categories of California cars  to meet increasingly stringent

emissions standards, to be phased in over time:  Transitional

Low-Emission  Vehicles;   Low-Emission  Vehicles;  Ultra-Low-

Emission  Vehicles;  and   Zero-Emission  Vehicles,  such  as

electric  cars.   California  has also  established  annually

descending  "fleet  average  requirements,"  based  on  sales

targets  for each  category  of vehicles.    A fleet  average

requirement is a cap on the average emissions attributable to

all classes of vehicles produced by a particular manufacturer

in a given year (in other words, the manufacturer's "fleet").

California's   requirements    provide   manufacturers   with

"flexibility to develop varying emissions within their entire

fleet to meet [an] overall goal."  MVMA, 17 F.3d at  535.  On
                                       

January 7, 1993, EPA granted California a   209(b) waiver for

the program.

          Meanwhile, on January 31, 1992, DEP adopted the LEV

component of California's  standards, intending to apply  the

standards beginning with 1995  models.  DEP regulations allow

new  California   cars  to  be  leased,   bought,  sold,  and

registered in Massachusetts,  but ban the  acquisition, sale,

                             -7-
                              7

and registration of  new federal  cars in the  state.   DEP's

proposed   regulations  sent  out   for  notice  and  comment

contained   fleet   average   requirements,   but   no   such

requirements appear  in the final rule  because DEP preferred

to let the market determine the mix of new California cars in

the state. 

C.        Prior Proceedings
                           

          Plaintiffs filed an  action in  the District  Court

for  the  District  of  Massachusetts,  arguing   that  DEP's

regulations are  preempted by  the Act because  DEP allegedly

failed  to comply with    177 of  the Act, 42  U.S.C.   7507.

Plaintiffs moved  for summary judgment and  for a preliminary

injunction, founding  their motions on four claims:   [1] the

regulations are not "identical"  to California's, in that DEP

did  not  adopt  California's  clean  fuels  rules;  [2]  the

regulations  force manufacturers to  create a "third vehicle"

because  of   the  higher  sulfur  content   of  gasoline  in

Massachusetts; [3] the regulations were adopted by DEP before

EPA  granted California a    209(b) waiver; and  [4] the two-

year  leadtime requirement  precluded DEP  from applying  the

regulations to any 1995 models because two automakers planned

to begin producing  1995 cars before  two years passed  after

the regulations were adopted.  

          With  the parties'  consent,  the court  stayed the

summary judgment  proceedings and  ruled first on  the motion

                             -8-
                              8

for a preliminary  injunction.  The  court denied the  motion

without a hearing, ruling that while  plaintiffs demonstrated

a  risk  of irreparable  injury  given  the cost  of  vehicle

emissions controls,  the balance of equities and  the risk of

harm to the public interest did not clearly favor granting an

injunction.   The court also found  that plaintiffs failed to

demonstrate a  likelihood of prevailing on  the merits, which

is  the "sine qua  non" of  the preliminary  injunction test.
                      

Weaver v. Henderson, 984 F.2d 11, 12 &amp; n.3 (1st Cir. 1993). 
                   

          Three of the four Clean Air Act issues presented to

the district court were later addressed by the Second Circuit

in  a case concerning a  challenge to New  York's adoption of

the  LEV standards.  See MVMA, 17  F.3d at 521, aff'g in part
                                                             

and rev'g in part Motor Vehicle Mfrs. Ass'n v. New York Dep't
                                                             

of  Envtl.  Conservation, 831  F.  Supp.  57 (N.D.N.Y.  1993)
                        

(hereinafter New York DEC).  The Second Circuit held in favor
                         

of  the state on the identicality and waiver claims, but held

in  favor of the  automakers on the  leadtime claim.   Id. at
                                                          

532-35.  The court  did not consider the merits of the "third

vehicle"  claim because  the  district  court found  material

facts at issue and set the claim down for trial.  Id. at 530.
                                                     

                             II.

                      PARTIAL DISMISSAL
                                       

          Prior to oral argument, plaintiffs moved under Fed.

R.   App.  P.  42(b)  to  dismiss  their  appeal  as  to  the

                             -9-
                              9

identicality,  waiver,  and  third  vehicle  claims,  thereby

leaving  the leadtime  issue as  the  sole basis  for interim

relief.    Plaintiffs'  action  was prompted  by  the  Second

Circuit's adverse  ruling  on  the  identicality  and  waiver

claims, which came after  plaintiffs' opening brief was filed

in  this case.    In addition,  plaintiffs maintain  that the

third  vehicle claim  requires  testimony on  the effects  of

sulfur  on emissions systems,  and that  the evidence  in the

record is outdated and incomplete.   

          We have broad discretion to grant voluntary motions

to dismiss.   "An appeal  may be  dismissed on motion  of the

appellant  upon such  terms as  may  be .  . .  fixed by  the

court."  Fed. R. App. P. 42(b); see also 16 Charles A. Wright
                                        

&amp; Arthur R. Miller, Federal Practice and Procedure   3988, at
                                                  

480 (1977).  Such  motions are generally granted, but  may be

denied  in  the interest  of justice  or  fairness.   See HCA
                                                             

Health Servs. of Virginia v. Metropolitan Life  Ins. Co., 957
                                                        

F.2d 120,  123 (4th Cir.  1992); United States  v. Washington
                                                             

Dep't of Fisheries, 573 F.2d 1117, 1118 (9th  Cir. 1978).    
                  

          DEP contends  that this  case "presents one  of the

rare occasions where justice requires that a voluntary motion

to dismiss be . . .  denied," so that we might rule  that the

third  vehicle claim  fails  as  a matter  of  law.   We  are

unpersuaded.  None  of the grounds that have compelled courts

                             -10-
                              10

to  deny voluntary motions to dismiss are present here.  See,
                                                            

e.g.,  Township of Benton v. County of Berrien, 570 F.2d 114,
                                              

118-19 (6th  Cir. 1978) (denying  motion to dismiss  filed by

one  of   two  appellants  because  dismissal   "would  be  a

meaningless  gesture,"  where  both  appellants  pressed same

arguments, and both would be affected by decision); Blount v.
                                                          

State  Bank &amp; Trust  Co., 425 F.2d  266, 266 (4th  Cir. 1970)
                        

(denying   appellant's  motion   to  dismiss,   but  granting

appellee's because  appellant violated briefing  schedule and

caused appellee to file  motion to dismiss); Local  53, Int'l
                                                             

Ass'n  of Heat and Frost Insulators v. Vogler, 407 F.2d 1047,
                                             

1055 (5th  Cir. 1969)  (denying motion  and affirming  on the

merits  because  motion  to  dismiss  was  based  on  unsound

argument that appeal from injunction was moot since appellant

was voluntarily refraining  from enjoined conduct); see  also
                                                             

Washington  Dep't  of Fisheries,  573  F.2d  at 1118  (courts
                               

"might have grounds" for denying motion to  dismiss if sought

to evade appellate review and to frustrate court orders).  

          Furthermore, we note that  granting the Rule  42(b)

motion will  not shelter the remaining  claims from scrutiny.

We will simply be accepting plaintiffs' decision to let those

claims be  finally adjudicated  before bringing them  to this

court.  Creaton  v. Heckler,  781 F.2d 1430,  1431 (9th  Cir.
                           

1986).   The interests of  fairness and judicial  economy are

well served by  restricting our review to the leadtime issue,

                             -11-
                              11

the  sole   claim  both  parties  concede   we  must  decide.

Consequently, we  grant the motion for  partial dismissal and

decline to reach the merits of the third vehicle claim.  

                             -12-
                              12

                             III.

                           LEADTIME
                                   

          We turn  to whether the district  court was correct

in  denying a  preliminary injunction  based on  the leadtime

claim.  We will reverse only if the district court abused its

discretion or  made a manifest  error of  law.   Narragansett
                                                             

Indian Tribe v. Guilbert, 934 F.2d 4, 5 (1st Cir. 1991).     
                        

          At issue is the proper construction of the leadtime

requirement.   The statute  at issue,   177  of the Clean Air

Act, 42 U.S.C.    7507, empowers states to adopt  and enforce

California emissions standards for vehicles and motor vehicle

engines  "for  any model  year,"  if  the state  adopts  such

standards  "at least  two years  before commencement  of such

model  year  (as  determined  by  regulations  of  the  [EPA]

Administrator)."2   The  parties  agree that  the model  year

                    

2.  Section 177 states, in pertinent part:
          Notwithstanding  [the statute  preempting
          state  emissions regulations],  any State
          which  has  plan   provisions  [for   the
          attainment and maintenance of  the NAAQS]
          may adopt and enforce for  any model year
          standards   relating    to   control   of
          emissions from new motor vehicles  or new
          motor vehicle engines . . . if --
          (1)  such standards are identical to  the
          California standards for  which a  waiver
          has been granted for such model year, and
          (2)  California and such State adopt such
          standards  at  least  two   years  before
          commencement  of  such  model   year  (as
          determined   by    regulations   of   the
          Administrator).
42 U.S.C.   7507.

                             -13-
                              13

designation of  any particular  vehicle depends on  when that

model or engine was produced.  According to EPA, a model year

is either the calendar year, or the manufacturer's production

period, lasting no  longer than  a day less  than two  years,

i.e., from January  2 of the preceding  year through December
    

31 of the  calendar year for which  the model year is  named.

40 C.F.R.    86.082-2  ("model year"  means calendar year  or

"the  manufacturer's annual production  period (as determined

by the [EPA] Administrator)"); EPA, Office of Mobile Sources,

Advisory  Circular 6B  (1987) (hereinafter  Advisory Circular

6B) (defining annual production period).3  

          The  parties dispute  whether or  not  the leadtime

requirement applies on an  industry-wide basis.  According to

plaintiffs,  all 1995  models sold  in Massachusetts  must be

federal  cars because  GM and  Chrysler began  producing 1995

models prior to  January 31, 1994.  In other words, the model

                    

3.  Advisory Circular 6B states, in pertinent part:
          The  "annual  production period"  for any
          specific model within an engine family of
          light-duty vehicles or heavy-duty engines
          begins either:  (1)  when such vehicle or
          engine  is  first  produced,  or  (2)  on
          January 2 of the calendar  year preceding
          the  year  for which  the  model year  is
          designated, whichever date is later.  The
          annual  production  period  ends  either:
          (1) when the last such vehicle  or engine
          is produced, or (2) on December 31 of the
          calendar year for which the model year is
          named, whichever date is sooner.

                             -14-
                              14

year began less than  two years after the LEV  standards were

adopted.  

          Basing its interpretation  on Advisory Circular 6B,

with support from EPA's amicus brief, DEP demurs, maintaining

that the leadtime requirement is satisfied as to any model in

an  "engine family"  first produced  after January  31, 1994.

The   record  indicates   that  an   "engine  family"   is  a

classification used to group  together vehicles that have the

same emissions  control design.  DEP's  standards would apply

only  to  models  or  engine families  first  produced  after

January   31,   1994.      Plaintiffs    characterize   DEP's

interpretation as "splitting" the model year because the 1995

standards would apply to some, but not all 1995 cars.

          The  district  court's position  approximated DEP's

(and EPA's):  "`The failure to provide the statutory leadtime

to a particular manufacturer for a particular model year does

not invalidate the standards  themselves.  Instead, it merely
              

renders  them unenforceable  as  against those  manufacturers

which  were  not  given  the  requisite  two-years  notice.'"

American Automobile  Mfrs. Ass'n v. Greenbaum,  No. 93-10799-
                                             

MA, slip op. at 23 (D. Mass. Oct. 27, 1993) (quoting New York
                                                             

DEC, 831 F.  Supp. at 64 (emphasis in original)).   The court
   

did  not rule on whether  each engine family  has a different

model  year  commencement  date,  but  noted  that   Advisory

                             -15-
                              15

Circular 6B "seems to  support DEP's understanding."   Id. at
                                                          

23 n.20.   

          Plaintiffs' industry-wide date for the commencement

of  the model  year prevailed  in the  Second Circuit.   That

court held that EPA's position  was not entitled to deference

because  it was  "newly  minted" for  litigation and  was not

embodied in a regulation under   177.  MVMA, 17  F.3d at 535.
                                           

Moreover,  the  court  found  an  industry-wide  date  to  be

consistent   with   Congressional    intent,   while    EPA's

interpretation was unprecedented  and "unreasonable"  because

it  would be  confusing to  the  industry and  impractical to

enforce.   Id. at 535-36.   Plaintiffs urge us  to follow the
              

Second Circuit.  We decline to do so. 

          In the  first place, we  are not confronted  with a

regulatory  program identical to that at  issue in the Second

Circuit.      New   York,   like   California,   but   unlike

Massachusetts,   imposed   fleet   average  requirements   to

determine  the mix of vehicles  sold in the  state each year.

The Second Circuit determined that the leadtime provision was

"best read"  with an industry-wide commencement  date because

splitting  the  year  would   "unduly  complicate  the  fleet

averaging  plan."  MVMA, 17 F.3d at 535.  Manufacturers would
                       

be  unable  to buy  and sell  emissions  credits to  meet the

requirements  because some of them would  have to comply with

1995 standards, but others would not.  Id.  We agree with the
                                          

                             -16-
                              16

Second Circuit that fleet averaging might be more complicated

in   the  first  year   that  California-type  standards  are

effective  in a   177 state, but we discount the significance

of   that  consideration.    Fleet  averaging  for  emissions

programs is  a concept  devised by California,  not Congress.

Although  the Second Circuit found fleet  averaging to be the

"crux" of the  LEV plan, id., neither party  in this case has
                            

argued that  under    177,  states must  adopt fleet  average

requirements.4   Accordingly,  the  extent to  which a  split

model    year    interpretation   unduly    complicates   the

administration  of  fleet   averaging  is  not   a  pertinent

consideration.  

          Furthermore,  we  do  not  agree  with  the  Second

Circuit's characterization of EPA's definition as having been

"newly  minted" for  litigation.   EPA  did  not develop  its

interpretation during litigation.  Rather, the  agency issued

Advisory   Circular  6B   in   1987,  while   New  York   and

Massachusetts adopted California's requirements in 1992.  And

in  a letter dated March 8, 1991, to Congressman John Dingell

(D. Mich.), the EPA  Administrator cited Advisory Circular 6B

for the  premise that "a state  adopting California emissions

standards  may apply  these  standards to  any engine  family

                    

4.  The automakers'  position during DEP's notice and comment
period for the LEV program (which originally included a fleet
averaging scheme) was that fleet averaging violates the third
                                                   
vehicle provision by restricting a manufacturer's ability  to
sell California cars in the state.  

                             -17-
                              17

whose  production period begins on a date which is beyond two

years past  the date that the standards were adopted . . . ."

It is  significant that  EPA's interpretation did  not spring

from  a litigator's  self-spun argument,  but arose  prior to

litigation,  and  was expressed  by  the  Administrator in  a

letter  to a member of  Congress from Michigan.   See Federal
                                                             

Labor Relations  Auth. v.  United States  Dep't of Navy,  941
                                                       

F.2d   49,  59   (1st   Cir.  1991)   (deferring  to   agency

interpretation first  announced  in amicus  brief  and  later

adopted as  "official" agency position by  agency director in

unpublished  letter); cf.  Martin v. Occupational  Safety and
                                                             

Health  Review Comm'n,  111 S.  Ct. 1171,  1179 (1991)  ("Our
                     

decisions indicate that agency `litigating positions' are not

entitled  to   deference  when  they  are   merely  appellate

counsel's  `post  hoc  rationalizations' for  agency  action,
                     

advanced for the first time in the reviewing court.").      

          Based  on  the  statutory  requirement  that "model

year" be  determined by  EPA regulations, the  Second Circuit

held  that  Congress intended  that  EPA  would promulgate  a

regulation  defining "model year" under   177.  MVMA, 17 F.3d
                                                    

at 535.  We  disagree.  We find that  a regulatory definition

predating   177 satisfies the statute.  Congress's use of the

passive  voice   indicates   that  an   existing   regulatory

definition  would suffice.  Compare    177, 42  U.S.C.   7507
                                   

("as determined by  regulations of the  Administrator") with,
                                                            

                             -18-
                              18

e.g.,  id.      7521(a)(1)  ("the  Administrator  shall"   by
          

regulation prescribe federal auto emission requirements).  In

1970,  Congress  passed  42  U.S.C.     7521(b)(3)(A),  which

defines  "model  year,"  for  the  purposes  of  the  federal

emissions control  program, as  the "calendar year,"  or "the

manufacturer's annual production period (as determined by the

[EPA]  Administrator)  which  includes   January  1  of  such

calendar year. .  . ."   The regulatory  definition of  model

year  in  effect  when      177  was  enacted  tracked   that

definition:  "`Model year' means [the  calendar year, or] the

manufacturer's annual production period (as determined by the

Administrator) which includes January 1 of such calendar year

. . . ."  40 C.F.R.   86.082-2. 

          We also  reject the  Second Circuit's  finding that

Congress  could  not  have  contemplated  that  the  leadtime

provision might apply  on an engine-family  basis.  MVMA,  17
                                                        

F.3d at 535.  We note first that what Congress "contemplated"

is  of  limited  relevance,  given  that  EPA  was  expressly

authorized  to   define  when   the  model  year   commences.

Moreover,  since  1972,  EPA has  issued  advisory  circulars

describing how to determine the  model year "for any specific

model within an engine family."  E.g., Advisory Circular  6A,
                                     

at 2  (Sept. 1, 1972).  And while EPA has never implemented a

split model year in the federal emissions control program, we

do not place great weight on  this.  There are relatively few

                             -19-
                              19

leadtime provisions  in the  Clean Air Act  emissions control

program.    Because  states  with     177  programs  are,  by

definition, encountering significant air  pollution problems,

and because Congress expressly delegated to EPA the power  to

define  model  year under     177,  EPA may  identify  policy

considerations   allowing  it   to   construe  the   leadtime

provisions  in the  federal program  differently from    177.

See  Comite pro Rescate de  la Salud v.  Puerto Rico Aqueduct
                                                             

and  Sewer Auth., 888 F.2d 180, 187 (1st Cir. 1989) ("[W]here
                

the reason  for the  court's `deference' reflects  its belief
          

that Congress, in effect, delegated to the agency a degree of
                                   

interpretive power, it does  not seem odd to find  the agency

interpreting  the same  words  somewhat  differently as  they

apply  to different parts of  the statute in  order better to

permit  that  statute to  fulfill  its  basic congressionally

determined  purposes." (emphasis in original)), cert. denied,
                                                            

494 U.S. 1029 (1990).  

          On  the other  hand, one  might argue that  a court

owes EPA's  interpretation no  deference because the  statute

requires EPA  to define  "model year" by  "regulation," while

EPA's  definition  is found  not in  a  regulation, but  in a

policy statement  (Advisory Circular 6B).  See  MVMA, 17 F.3d
                                                    

at  535 ("Section 177 charges the EPA with the single, narrow

responsibility to issue `regulations'  in order to define the

commencement of a  model year under   177.   The EPA Advisory

                             -20-
                              20

Circular  . . . is not a  `regulation' for   177 purposes and

was not promulgated specifically to implement  this provision

. . . .").  Plaintiffs failed to make such an argument to the

district  court and  compounded  that error  by omitting  the

point from their  opening brief.5  See McCoy v. MIT, 950 F.2d
                                                   

13, 22 (1st Cir. 1991) ("It is hornbook law that theories not

raised squarely in  the district court cannot be surfaced for

the  first time on appeal."),  cert. denied, 112  S. Ct. 1939
                                           

(1992);  see also Frazier v.  Bailey, 957 F.2d  920, 932 n.14
                                    

(1st Cir. 1992)  (arguments raised  only in  reply brief  are

insufficient  to preserve  claim  on appeal).   Until  filing

their reply brief in this  court, plaintiffs failed to assert

that no EPA definition of model year existed for the purposes

of    177,  and in  fact cited  Advisory Circular  6B and  40

C.F.R.    86.082-2 to the district court for the premise that

the  model year  began  on  January  2,  1994.    See,  e.g.,
                                                            

Plaintiff's Mem. of Law  in Support of Mot. for S.J.,  at 44;

First  Amended   Complaint      55  ("As  defined   by  EPA's

regulations,  the  1995  model  year commences  as  early  as

January 2, 1994.  See 40 C.F.R.   86-082-2 (1992); EPA Office
                     

of Mobile Sources Circular 6B (1987).").

                    

5.  Plaintiffs argued  below and in their  opening brief that
Congress's use  of the terms "commencement"  and "model year"
in the singular foreclosed a "split" model year, that such an
interpretation would  have adverse  effects on  the industry,
and that EPA had never used a split model year in the federal
emissions control program.  

                             -21-
                              21

          We have recognized  an exception  to the  raise-or-

waive rule where the argument surfacing for the first time on

appeal is "`so compelling  as virtually to insure appellant's

success,'" and  a  "`gross  miscarriage  of  justice'"  would

result from our failure  to address it.  Johnston  v. Holiday
                                                             

Inns,  Inc., 595  F.2d  890, 894  (1st Cir.  1979) (citations
           

omitted); accord United States v. Slade, 980 F.2d 27, 31 (1st
                                       

Cir. 1992).   The argument  here is not  so compelling as  to

assure plaintiffs'  success.   EPA's interpretation of    177

would be entitled to  some weight, where EPA  administers the

federal  emissions  program and  is  charged with  evaluating

whether state plans for meeting the NAAQS are consistent with

the Act.  See 42 U.S.C.   7410(k)(3).  
             

          Furthermore, plaintiffs  do  not contend  that  our

failure  to  consider  the   argument  would  cause  a  gross

miscarriage of justice.  Nor could  they so contend.  In  the

first place, this is  an interlocutory appeal; plaintiffs may

raise  the  argument  in  the district  court  before  issues

pertaining to the 1995  requirements become moot, because the

model year for any vehicle lasts until December 31, 1995.  In

addition, this is not a case in which an appellant might lose

her home, see  United States v. One Urban Lot,  885 F.2d 994,
                                             

1001-02  (1st   Cir.  1989),  or  a   prisoner  might  remain

incarcerated, see United States v. La Guardia, 902 F.2d 1010,
                                             

1013  (1st Cir.  1990), if  we deem  the issue  waived.   And

                             -22-
                              22

though the  question before us, concerning  the earliest date

vehicles  outside California might  be subject to California-

type emissions standards, is certainly one of interest to the

public, the degree of public interest pales in contrast  with

that  involved  when  the   federal  government's  right   to

prosecute  suspected  criminals  is at  issue,  e.g.,  United
                                                             

States v. Krynicki, 689 F.2d 289, 292 (1st Cir. 1982).  These
                  

cases show the gulf that exists between  the prospective harm

here and  the type of harm that permits serious consideration

of  relaxing the  raise-or-waive  rule, within  the reviewing

court's discretion.  Accordingly, we find the argument waived

for the purposes of this appeal.

          Assuming, therefore, that the regulatory definition

of  model  year required  by    177  is embodied  in Advisory

Circular 6B, we next  inquire whether EPA's interpretation is

arbitrary, capricious, or manifestly contrary to the statute.

Chevron U.S.A.,  Inc. v. Natural  Resources Defense  Council,
                                                            

467 U.S. 837, 843-44  (1984).  Such deference is  due because

Congress explicitly  delegated to EPA, the agency responsible

for administering the federal  emissions program, the task of

defining model year under   177.  

          Plaintiffs   argue   that  applying   the  leadtime

requirement  to   individual   models  or   engine   families

contradicts Congress's intent made manifest by the  statute's

use  of  the terms  "commencement"  and "model  year"  in the

                             -23-
                              23

singular.  We disagree.   At best, the statutory  language is

ambiguous  with respect to  whether the  leadtime requirement

might  apply on  an  industry-wide or  engine-family-specific

basis.  See  42 U.S.C.    7507 (State "may adopt  and enforce
           

[standards] for  any model year .  . . if-- .  . . California

and such State adopt such standards at least two years before

commencement of such model year . . . .").  An examination of

other  leadtime  provisions enacted  in  1977  for the  Act's

federal emissions program does  not clarify the issue because

those  provisions generally  pertain  to heavy  duty engines,

whose model year commencement  date, according to the record,

is  always January 1 of  the calendar year.   Moreover, those

provisions could  be read with either  an industry-wide model

year  commencement  date,  or separate  dates  for  different

engine families.  E.g.,  42 U.S.C.   7521(a)(3)(E)(ii) (1988)
                      

("No such  changed standard  shall apply  for any model  year

before  the model year four years after the model year during

which  regulations  containing   such  changed  standard  are

promulgated.") (repealed in 1990).  

          Moreover,  the  legislative  history of     177  is

generally  unenlightening.6    Congress clearly  enacted  the

                    

6.  Plaintiffs,  in a  footnote,  quote a  1990 statement  of
Senator Nickles:
          If   a   State   follows  the   necessary
          procedures, California standards can take
          effect in the first model year commencing
          2 model years after the State has adopted
          the  California standards.  Thus, a State

                             -24-
                              24

leadtime provision for the manufacturers' benefit.  H.R. Rep.

No. 294, 95th Cong., 1st Sess. 310 (1977) ("Manufacturers are

not  only   assured  of   identity  of  standards   and  test

procedures; they are also  assured adequate lead time."); see
                                                             

also  MVMA, 17 F.3d at 535.  Although plaintiffs would prefer
          

that  all  1995  cars  be  subject  to  the  same  regulatory

requirements,  that is  not  necessarily the  import of  that

statement of legislative intent.  EPA's interpretation grants

every  manufacturer two years  to develop  emissions controls

and to  devise marketing and distribution  strategies for any

new vehicle  or  engine  family  subject  to  California-type

standards.    There is  no  inherent  conflict between  EPA's

interpretation and Congress's intent.7

          Plaintiffs maintain that EPA's  interpretation does

not  reflect  a reasonable  policy  determination  because it

would cause "enormous competitive and practical problems," in

that California-type  requirements would apply  to some  1995

                    

          that  adopted   fully  waived  California
          standards  in  November  1992 could,  for
          example, have those standards take effect
          beginning in model year 1996. 
136 Cong. Rec. S18274 (daily ed. Nov. 2, 1990).  The leadtime
provision  was enacted in 1977  and was not  amended in 1990.
We give  little weight to  the remarks of a  single member of
Congress, made thirteen years after  a statute is passed,  in
divining legislative intent.   

7.  DEP  notes  that  EPA's interpretation  has  one salutary
effect for the industry:   each manufacturer could determine,
from  its  own production  schedules,  not  the schedules  of
others, whether to produce federal or California cars for the
first year in which California-type standards are in effect.

                             -25-
                              25

vehicles,  while the  remainder would  be subject  to federal

standards.   Appellants' Br. at 46.  According to plaintiffs,

this  split would  cause dealer  and consumer  confusion, the

disruption of vehicle  distribution systems, and  competitive

disadvantages  for  some  dealers  and  manufacturers.    DEP

argues, however,  that these  concerns are  overstated, given

the widespread use of computerized inventory controls.  Also,

on  the other side of the balance  is the state's interest in

applying California  requirements to  some models as  soon as

possible.  Any vehicle subject to regulatory controls will be

subject  to those  controls  for the  vehicle's useful  life.

Conversely, vehicles  escaping the  controls may travel  over

Massachusetts  highways  for  years  emitting  pollutants  in

excess of California standards.  Whether EPA's interpretation

imposes   greater   costs   than   benefits   is   a   policy

determination.  "When Congress, through express delegation or

the  introduction of  an  interpretive gap  in the  statutory

structure,  has  delegated  policy  making  authority  to  an

administrative agency,  the extent of judicial  review of the

agency's  policy  determinations  is   limited."    Pauly  v.
                                                         

Bethenergy Mines, Inc.,  111 S.  Ct. 2524, 2534  (1991).   We
                      

will  reject  the  agency's  interpretation  only  if  it  is

arbitrary  or illegal.  It is neither.  Accordingly, based on

the  assumption   that  Advisory  Circular   6B  provides   a

                             -26-
                              26

regulatory definition of "model  year" for the purposes  of  

177, we conclude that the leadtime requirement was satisfied.

          The  likelihood  of  success  on the  merits  is  a

predicate  to  the  issuance  of  a  preliminary  injunction.

Plaintiffs failed to establish  such a likelihood.  Moreover,

plaintiffs  "have  not  persuaded  us that  the  lower  court

overlooked  pertinent  factors,   focused  on   inappropriate

factors,  or made a  serious error in  weighing and balancing

the  relevant concerns."  Weaver, 984 F.2d at 14.  Therefore,
                                

we  hold that the district court did not abuse its discretion

in refusing to enjoin the 1995 standards.

                             -27-
                              27

                             IV.

                        COSTS AND FEES
                                      

          DEP  argues  that  it  is  entitled  to  costs  and

attorney's fees.  Prevailing parties are normally entitled to

costs.  Fed. R. App. P. 39; 9 James W. Moore  et al., Federal
                                                             

Practice   239.02[1],  at 39-6  to -7  (2d ed.  1994).8   And
        

costs are  routinely available whenever this  court dismisses

an  appeal, even if the  appellant moved for  dismissal.  See
                                                             

Waldrop v. Department of Air Force, 688 F.2d 36, 37 (7th Cir.
                                  

1982).  

          On  the other  hand, DEP's argument  for attorney's

fees must  be rejected.   DEP  seeks reimbursement  for legal

fees  incurred in responding to the appeal on the claims that

were dismissed  pursuant to Rule  42(b).  Neither  Rule 42(b)

nor  Rule  39  provides   authority  for  routine  awards  of

attorney's  fees  as  a  condition  of  voluntary  dismissal.

Waldrop, 688  F.2d at 37-39.  While fees may be awarded if an
       

appellant  has filed a frivolous  appeal or has  acted in bad

faith, see Cruz  v. Savage,  896 F.2d 626,  631-32, 635  (1st
                          

Cir. 1990), we find no evidence of such conduct here.  We are

                    

8.  Rule 39 states:
          Except as otherwise  provided by law,  if
          an  appeal is  dismissed, costs  shall be
          taxed   against   the  appellant   unless
          otherwise . . . ordered by the court; . .
          . if  a judgment is affirmed  or reversed
          in part,  or is vacated,  costs shall  be
          allowed only as ordered by the court.  

                             -28-
                              28

unpersuaded by  DEP's attempt to characterize  the weeks that

transpired between the issuance of the Second Circuit opinion

and  the   motion  for  partial  dismissal   as  evidence  of

plaintiffs' vexatiousness.   It takes time to  evaluate a new

opinion,  and to  confer with  the client  on an  appropriate

strategy.  

                              V.

                          CONCLUSION
                                    

          For the foregoing reasons,  we grant the motion for

partial dismissal  and affirm the  district court's  decision

not  to enjoin  the  1995 requirements  based on  plaintiffs'

leadtime claim.  Costs to DEP.

          It is so ordered.
                           

                             -29-
                              29
