The Obama administration is looking to close down the automotive aftermarket. Tucked deep within a proposed rulemaking governing diesel truck engines, the Environmental Protection Agency (EPA) and National Highway Traffic Safety Administration (NHTSA) introduced language that would prohibit any changes to an automobile's engine or exhaust after it leaves the factory. The Specialty Equipment Market Association (SEMA) raised the alarm Monday after discovering the hidden provision.

"Certified motor vehicles and motor vehicle engines and their emission control devices must remain in their certified configuration even if they are used solely for competition or if they become nonroad vehicles or engines," the proposed regulation states. "Anyone modifying a certified motor vehicle or motor vehicle engine for any reason is subject to the tampering and defeat device prohibitions of this section and 42 USC 7522(a)(3)."

The public comment period on the rule change closed last October. After the final rule is published in the Federal Register, it will have the force of law. The new regulation clarifies that road vehicles that are certified for sale in the United States can still be raced -- as long as the catalytic converters and other equipment remain untouched.

"If a motor vehicle is covered by a certificate of conformity at any point, there is no exemption from the tampering and defeat-device prohibitions that would allow for converting the engine or vehicle for competition use," the proposed rule states. "There is no prohibition against actual use of certified motor vehicles or motor vehicle engines for competition purposes; however, it is not permissible to remove a motor vehicle or motor vehicle engine from its certified configuration regardless of the purpose for doing so."

Under existing regulations, engines produced for racing do not need to meet any emissions standards, and a road car's engine may be modified for use in racing and offered for commercial sale without specific EPA approval (40 CFR 1068.235). Many automotive tuner shops sell parts designed for the race track to individuals interested in boosting the performance of their street vehicles. The EPA intends to close that market permanently by prohibiting the sale of high-performance engine and exhaust parts.

SEMA, which represents the $36 billion aftermarket industry, is furious and intends to battle the proposal in court. The group argues that the federal agencies violated public notice requirements by hiding the controversial proposal in a proceeding that has nothing to do with automobiles.

"This proposed regulation represents overreaching by the agency, runs contrary to the law and defies decades of racing activity where EPA has acknowledged and allowed conversion of vehicles," SEMA President Chris Kersting said in a statement. "Congress did not intend the original Clean Air Act to extend to vehicles modified for racing and has re-enforced that intent on more than one occasion."

The administration's hostility to performance cars is not new. It denied long-standing regulatory exemptions to low-volume manufacturers like Lotus, forcing the British automaker out of the US market. The administration has also sought to downplay the use of internal combustion engines in autoracing in favor of battery-powered vehicles through its "Green Racing Initiative," claiming the change of focus will prevent global warming.

"The goal of green racing is to use motor sport competition to help rapidly develop cleaner, more fuel efficient vehicle propulsion systems that will eventually be used in consumer vehicles," the EPA stated in a 2010 news release. "The high level of interest in motor sports could bring this technology to the attention of the public and hasten its acceptance in the new market."