Big 3 Petition EPA for CAFE Relief

I wonder why it wouldn't be a good idea to just freeze the EPA vehicle pollution regs at their present levels. My 2013 doesn't ever smoke, even at startup. There is NO diesel smell coming out of the tailpipe. It has a DPF and uses DEF. Haven't we reached the 90 percent solution ?? It's impossible to get to '0' and still build an affordable (kind of) fossil fuel burning vehicle.

Seems like if every country adopted current US pollution standards the world would be just fine.