It shouldn't be ignored, but this sort of thing pops up over there fairly regularly. SEMA are quite effective at lobbying Senators on issues that affect their members and have even got their own legislation passed for things like registration of home built vehicles (hot rods) in some states. They have also managed to get proposals like this overturned before.
Not completely sure but I think each state would have to pass this as a new law as well - there is no overall governance. Some states don't even have a smog test, others are quite strict.
The best thing to do is pass on accurate information to those in the US, so they can group up with SEMA and add further weight to the concerns raised.