Update: The Environmental Protection Agency announced on April 15 that it's withdrawing its proposed ban on modifying emissions controls for track use, following an uproar from performance car fans. But if you want to know the story behind the uproar, keep reading. It's proof that public pressure works!

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Sure, the EPA’s position on combating climate change gets some people riled, but what really stirs things up is the agency’s new approach to car racing.

It makes sense that the EPA would look askance at 8,000-horsepower dragsters with no mufflers, but traditionally the agency hasn’t much bothered with regulating off-road sports like racing. Until now. On March 2, the EPA issued the soporifically titled “Greenhouse Gas Emissions and Fuel Efficiency Standards for Medium- and Heavy-Duty Engines and Vehicles—Phase Two.” In it was a proposal (originally made last year, but no one noticed) that would make it a crime for anyone to remove a car’s pollution controls to turn it into a racing car.

That presumably covers a lot of ground, because the first thing racers do is remove the horsepower-robbing pollution controls. There was an immediate uproar, which hasn’t died down. On Tuesday (April 12), three Republican congressmen sent a letter to EPA Administrator Gina McCarthy expressing concern. “There are thousands of racing enthusiasts who own these vehicles and who have every reason to believe that what they were doing was legal,” they wrote. “Overnight, these vehicle owners may be considered lawbreakers and subject to penalties similar to those Volkswagen now faces.”

Porsche Carrera What Porsche owner doesn't dream of taking his or her car to the track? (Photo: Knockhill/flickr)

The EPA is in a comment period on the new regulation, with a final rule expected in July.In case you were wondering, NASCAR vehicles may look (vaguely) stock but these days they run engines built especially for them, and thus exempt from the Clean Air Act. But that didn't stop U.S. Rep. Richard Hudson (R-N.C.), whose district includes the Charlotte Motor Speedway, from calling the legislation "ridiculous government overreach."

The Specialty Equipment Market Association (SEMA), representing a lot of companies that make racing parts, is up in arms. SEMA says the new stance contradicts long-standing agency policy, which “recognized that vehicles used solely for competition are excluded from the EPA’s regulations under the Clean Air Act.”

According to Steve McDonald, SEMA’s government affairs VP, the EPA ruling "would put racers and many automotive aftermarket companies at risk of penalties and elimination. It would effectively ban the act of modifying your street car into a dedicated race car, and devastate the $36 billion automotive aftermarket industry that racing supports."

No more hot rods and tuned muscle cars, I guess. But the battle is just being joined. SEMA is supporting an alternative bill, H.R. 4715/S. 2659, the Recognizing the Protection of Motorsports Act of 2016 (RPM). It specifically enshrines the sacred American rite of hopping up a car for exclusive track use. Maybe Republicans care more about racing than Democrats do, because in keeping with that GOP letter to McCarthy the sponsors of the RPM Act are overwhelmingly on the red side of the aisle (though there are four Democrats). And they do like their NASCAR in Texas.

The Auto Alliance, which has 12 carmaker members, is also fighting the EPA rule. It says that thousands of vehicles get converted to competition or off-road use every year, and the new law would turn them all into criminals. The Alliance proposes a modification to the law with a loophole big enough for a Mack truck. Modifying emissions equipment should be prohibited “unless good engineering judgment or emissions testing provides a reasonable basis for knowing that a modification will not affect emissions performance.” That would likely make any enforcement impossible, because who’s going to legally define “good engineering judgment”?

racing Mustang Is this Boss 302 Mustang factory intact? Suuure it is. (Photo: Chad Horwedel/flickr)

For its part, the EPA says it’s not against car racing. “People may use EPA-certified motor vehicles for competition,” the agency said, “but to protect public health from air pollution” they just can’t tamper with the factory-installed emission controls. The EPA claims this isn’t a change from past policy, but the critics insist it’s a big change in interpretation.

One trade association, not surprisingly, does support the EPA. It’s the Manufacturers of Emission Controls Association (MECA). “Many of these [specialty part] purchases occur over the Internet, so there is no way to insure that the vehicle that is being tampered [with] is used solely for the purpose of racing and never driven on public roads,” MECA said.

It’s just a guess, but let me suggest that the EPA probably won’t win this one. Millions of incensed race and muscle car fans constitute a powerful voting constituency.

Here's an outraged racing fan on the EPA's proposed rule:

Jim Motavalli ( @jmotavalli ) writes about cars, technology and the environmental world to anyone curious enough to ask.