Will a from the Environmental Protection Agency really hinder your plans to turn your daily driver into a badass track-only machine? It will, officials from aftermarket trade association SEMA and the EPA itself confirmed to Jalopnik today. Here’s what all of this means.

This story was originally published on February 9, 2016

How far would the Environmental Protection Agency go to cut greenhouse emissions on vehicles?…

Last night , in the interest of reducing greenhouse gas emissions, would “prohibit conversion of vehicles originally designed for on-road use into race cars” and “make the sale of certain products for use on such vehicles illegal,” in their words.

Naturally this sparked a wildfire of controversy in the tuning and racing communities. Suddenly the ability to participate in grassroots racing series like LeMons, Spec E30, AER and more seemed in doubt. But it wasn’t immediately clear, in the pages and pages of regulations and proposed red tape, .

If an alarming press release from the aftermarket barons at SEMA is to be believed, our days…

In truth SEMA’s contention has to do with the EPA’s “clarifying”—or changing, if you ask the association—of a longstanding provision in the Clean Air Act, which for decades pretty much ignored the emissions of non-street legal race cars. Competition-only vehicles were excluded before, but now the EPA is claiming authority over those kinds of vehicles, said Steve McDonald, SEMA’s vice president for government affairs.

“The EPA claims we’ve been wrong all along,” McDonald told Jalopnik today.

The effect of this change, McDonald said, is not only the possible banning of racing parts that don’t meet emissions, but also the act of modifying your car in such a way—although he admitted the government is far more likely to go after parts makers than individuals. (This is why SEMA, which represents the aftermarket business and lobbies on its behalf, is involved with the situation.)

In all the 629 pages and thousands of words in , perhaps none are as important as “nonroad.”

The EPA has a very specific definition of “.” Agricultural equipment, lawn mowers, industrial machines, those are all nonroad vehicles. The most important thing is that they aren’t cars—car emissions are regulated entirely differently.

But, on page 40,539 of that Federal Register document, the EPA is attempting to make this change, emphasis mine:

Second, we are proposing to clarify the language describing how to manage the precision of emission results, both for measured values and for calculating values when applying a deterioration factor. This involves a new reference to the rounding procedures in 40 CFR part 1065 to replace the references to outdated ASTM procedures. An existing provision in 40 CFR 1068.235 provides an exemption for nonroad engines converted for competition use. This provision reflects the explicit exclusion of engines used solely for competition from the CAA definition of ‘‘nonroad engine’’.

Basically, the EPA wants to make clear that an exemption for turning nonroad vehicles (and engines) into competitive vehicles does not apply to your street car, even if it’s a track-only car.

McDonald said that for decades, the Clean Air Act was understood not to apply to competitive vehicles, but now the EPA contends that has never been the case. Indeed, the EPA has confirmed as much in its own statements to the public:

People may use EPA-certified motor vehicles for competition, but to protect public health from air pollution, the Clean Air Act has – since its inception – specifically prohibited tampering with or defeating the emission control systems on those vehicles.

The proposed regulation that SEMA has commented on does not change this long-standing law, or approach. Instead, the proposed language in the Heavy-Duty Greenhouse Gas rulemaking simply clarifies the distinction between motor vehicles and nonroad vehicles such as dirt bikes and snowmobiles. Unlike motor vehicles – which include cars, light trucks, and highway motorcycles – nonroad vehicles may, under certain circumstances, be modified for use in competitive events in ways that would otherwise be prohibited by the Clean Air Act.

The EPA added this as well:

This clarification does not affect EPA’s enforcement authority. It is still illegal to tamper with or defeat the emission control systems of motor vehicles. In the course of selecting cases for enforcement, the EPA has and will continue to consider whether the tampered vehicle is used exclusively for competition.

The EPA remains primarily concerned with cases where the tampered vehicle is used on public roads, and more specifically with aftermarket manufacturers who sell devices that defeat emission control systems on vehicles used on public roads.

McDonald said the EPA confirmed as much to his association too during a meeting on Jan. 20 with the agency’s Office of Enforcement and Compliance Assurance.

“All I can tell you is we went there with the intent of confirming whether (the EPA sought) to prohibit the conversion of certified vehicles into race cars,” he said. “They confirmed that.”

So what does all of that mean? McDonald and SEMA fear a crackdown on the manufacturing of emissions-related parts for racing use. Previously, track-only, non-street legal vehicles could contain parts that didn’t meet emissions standards. The EPA has something else in mind now, and McDonald says it could put a meteor-sized dent in the $36 billion parts industry—not to mention grassroots racers everywhere.

And it still could become technically illegal for someone to modify their car for racing in a way that doesn’t meet emissions regulations. One section in the document said the EPA “may assess a civil penalty up to $37,500 for each engine or piece of equipment in violation,” though the EPA says it cares more about these cars being used on public roads and manufacturers.

It must be noted again that this proposed rule deals specifically with emissions, not other racing modifications like suspensions or roll cages. But it’s hard to imagine a race car performing to its full potential if its builder has to worry about meeting emissions regs, no matter what series it competes in.

“Vehicles used on the street and track are restricted by environmental regulations,” McDonald. “We contend that if you convert a vehicle into a race car, and it only gets tracked, that is excluded.” But the EPA claims it’s always been this way, and the agency is simply clarifying the rule.

Moreover, SEMA is accusing the EPA of essentially pulling a fast one on the auto parts industry and the public. McDonald said the provision was buried in an “unrelated” set of rules about greenhouse gas emissions for medium and heavy duty vehicles last summer, which is why it took months for it to become public. SEMA itself only learned about it late last year.

“We feel the EPA failed on all counts,” McDonald said. “They did not give the public adequate notice.”

What happens now? McDonald said it’s a long process. The EPA could issue a final rule by July, or possibly longer. After that, it becomes law—no Congressional approval required. SEMA, however, will continue to oppose the effort through lobbying and possibly litigation.

As for the EPA, they’ll be listening too.

“(The agency) is reviewing public comments on this proposal,” it said in a statement.