Answering a challenge from a discussion with friends, wherein it was pointed out that, as a champion of free markets, I had never cited an example of regulation I favored:
I don't like CAFE regulation, not as it's practiced, but not because it's undue interference in the market–it's not. I disagree with Ed Wallace (author of link below) as often as I agree with him, but he makes disagreement hard as his facts are nearly always impeccable–I have to search very hard to find the bits and pieces he might miss, if he does at all (and then I have no choice but to re-evaluate my position). Does a great bit on his radio show called the Backside of American History.
FWIW, Ed and I agree on what the flaws in CAFE are as well and they have to do with the loopholes that avoid the regulation (for producing ethanol using cars primarily).