Let us count the ways that this is stupid. For one MANY of the race teams and companies that build components for them are small American businesses. This regulation would have the potential to shut down plenty of those small companies.
Compared to the total number of older cars on the road and the number of semi trucks criss-crossing our country every day, the carbon emissions put out by grassroots motorsports is minimal. One area where I have no problem with the EPA cracking down is on trucks that are chipped to “roll coal.” But to come down on some guy autocrossing his Miata on Saturdays seems a little nuts.