[Big Dave]

You may think the imaginary degradation in PM2.5 offsets the loss of MPG. I don't. I have worked enough with the EPA to know just how thin the evidence for such claims are.

Although I equally do not buy the Global Warming hooey, I do get a chuckle from this. For the imaginary benefits of reduced PM2.5 you lose the imaginary benefits of reduced CO2 emissions that a more efficient engine brings you. Further, compliance with the PM2.5 standard involve generating even more CO2 for no good reason.

It seems with environmental extremists and faux public health "experts" on the make for grant funding, nothing is ever good enough.

Also DPF standards are only enforceable on new vehicles. I cut mine off and the EPA has no way to find out.