The EPA has made illegal carrying certain flammable substances in your
 vehicle. I can just imagine the EPA announcing its latest law:
 
    As methane has been determined to be flammable, it shall henceforth be
    illegal to fart in any motor vehicle while such motor vehicle is in
    motion. In addition, it shall be illegal to set any motor vehicle in
    motion so long as the fumes produced by a prior fart are detectable in
    said motor vehicle. The determination that fumes are no longer present
    shall be made by someone other than the individual who produced the
    fart, as it has been experimentally verified that people are apparently
    quite immune to the effects of their own farts.
 
    In addition to the usual fine for such offenses, anyone stopped by a law
    enforcement official and found guilty of this infraction shall be fined
    an additional $50 - $100 (depending on the potency of the fart) for
    causing said law enforcement official excessive nasal discomfort.