[jyl]

As I read it, these are very minor improvements, or perhaps are not improvements at all.

The new regulations divide the light truck market into six groups and sets fuel economy standards for each group, rather than requiring an automaker's entire light truck production to meet an overall fuel economy standard.

This means that an automaker can concentrate on selling just the bigger and heavier SUVs and pickup trucks, that get the worst fuel economy. There won't be a need to also develop and sell the lighter, more fuel efficient vehicles to balance out the gas-guzzlers.

For example, GM could concentrate on Suburbans and Hummers (actually I think the Hummer might even be exempt from CAFE) and not bother to market smaller SUVs or develop hybrid SUVs.

This looks like a CAFE standard written by Detroit lobbyists.