                               ATTORNEY GENERAL OF TEXAS
                                            GREG        ABBOTT




                                                 August 9, 2011



The Honorable Phil Garrett                                Opinion No. GA-0873
Palo Pinto County Attorney
Post Office Box 190                                       Re: Whether there is an exception for diesel
Palo Pinto, Texas 76484                                   turbine engines to the requirement that all vehicles
                                                          have a muffler (RQ-0949-GA)

Dear Mr. Garrett:

       You ask whether motor vehicles equipped with a diesel turbine engine are excepted from the
requirement that all vehicles have a muffler. 1

         Section 547.604 of the Transportation Code provides, in relevant part:

                         (a) A motor vehicle shall be equipped with a muffler in good
                  working condition that continually operates to prevent excessive or
                  unusual noise.

TEX. TRANSP. CODE ANN. § 547.604 (West 1999). For purposes of subtitle C, title 6 of the
Transportation Code, of which section 547.604 is a part, a "muffler" is defined to mean "a device.
that reduces noise using: (A) a mechanical design, including a series of chambers or baffle plates,
to receive exhaust gas from an internal combustion engine; or (B) turbine wheels to receive exhaust
gas from a diesel engine." Id § 541.203. Your request letter indicates that some have suggested that
the second definition of "muffler" excludes a "diesel turbine engine" from the separate muffler
requirement described by the first defmition. Notwithstanding the type of noise reduction
mechanism utilized by a specific muffler, section 547.604 requires that a vehicle have a
device-specifically a "muffler"-that "reduces noise."

       Under section 547.604 of the Transportation Code, a motor vehicle is required to be equipped
with a "muffler" and the statute directs that the term "muffler" may consist of either one of the
following: "(A) a mechanical design, including a series of chambers or baffle plates, to receive
exhaust gas from an internal combustion engine; or (B) turbine wheels to receive exhaust gas from


        'Letter from Honorable Phil Garrett, Palo Pinto County Attorney, to Chairperson, Opinion Conunittee, Attorney
General of Texas at 1 (Mar. 3, 2011), https://www.oag.state.tx.us/opin/indexJq.shttnl ("Request Letter").
The Honorable Phil Garrett - Page 2             (GA-0873)



a diesel engine." See id. § 547.604. As we have noted, your request letter indicates that some have
contended that a "diesel turbine engine" is itself equivalent to "turbine wheels to receive exhaust gas
from a diesel engine." Whether a particular diesel turbine engine satisfies the statutory definition
is a fact question that falls outside the purview of the opinion process. However, section 547.604
plainly requires that motor vehicles "have a device that reduces noise." Accordingly, to satisfy this
provision of the Transportation Code, motor vehicles must have a muffler that reduces noise.
The Honorable Phil Garrett - Page 3            (GA-0873)



                                       SUMMARY

                      A motor vehicle must be equipped with a "muffler," which is
               defined in part as "a device that reduces noise." Accordingly, in order
               to meet the requirement of section 547.604 of the Transportation
               Code, a vehicle must be equipped with a muffler that reduces noise.

                                              Very truly yours,




                                              Attorney General of Texas


DANIEL T. HODGE
First Assistant Attorney General

DAVID J. SCHENCK
Deputy Attorney General for Legal Counsel

JASON BOATRIGHT
Chair, Opinion Committee

Rick Gilpin
Assistant Attorney General, Opinion Committee
