I would also appreciate it if the CA legislature could explain the science behind our special reformulated gasoline that costs between $0.50 and $1.00 more than gasoline in surrounding states (CA consumes 15B gallons/year). Or is it just too tempting to keep the prices inflated so that the gasoline tax revenue received in Sacramento is also inflated?

I hate that the media is conflating "emissions standards" and fuel efficiency. Pruitt isn't rolling back anything to do with particulates, nitrous oxides, hydrocarbons, etc - all the stuff that causes smog and dirt. Those rules are staying for good. What is happening is that he's relaxing the CAFE requirements (corporate average fuel economy).

The CAFE requirements are too strict. They've lead to complex technologies such as direct injection, twin-charging, turbos, CVT's, 10 speed transmissions. All these technologies do indeed improve fuel efficiency, but at a severe cost to reliability, and for a high cost. The sweet spot of nice, reliable cars is behind us, and we're getting more expensive, more complicated cars which break more. So, in my book, this is a good change. These standards only apply to new cars, and leave old, grossly polluting cars on the road, the net win given the cost isn't so great.