I was mistaken to assume that the Corporate Average Fuel Economy standards were just that. The truth reveals that manufacturers are to improve the fuel economy of each GROUP of vehicles, such as compacts, intermediates, by a certain percentage each year.
This was based on a vehicle sales mix in the past when gas prices were HIGH, and truck sales were much lower. The 56 or so overall MPG was to be achieved that way.
Unfortunately with low gas prices truck sales are now a much higher share of the market and the 56 mpg overall gas mileage figures will NOT BE ACHIEVED. At the present sales mix, 50 mpg would be maximum.
If the purpose is to reduce greenhouse gasses, this program is not very effective. It has essentially let the US carmakers off the hook so they don’t have to sell a lot of small cars which they are not very good at.
European makers, on the other hand will be sales rated in average grams per kilometer for their entire fleet. Mercedes is really under the gun here and will push their SMART CARS there to help the average.
In short the future CAFE is a lie the way it will be implemented in to future. I apologize for overlooking this weasel clause.