The White House issued new rules for heavy vehicles like "tractor-trailers, buses, delivery vans, heavy pickup trucks, [and] cement mixers." They will have to reduce fuel consumption, and greenhouse-gas emissions by 10 to 20 percent, depending on the type of truck, over the next eight years.
The rules were issued by the Environmental Protection Agency, and they don't need congressional approval, which is good for Obama because Republicans have a tendency to not believe in man-made global warming. They were not as ambitious as some scientists wanted, both as a way of keeping costs under control and making nice with worried businesses.
It will be a year until the rules to go into effect, more than enough time for new Republican congressmen to paint EPA Administrator Lisa Jackson as some America-destroying green freak.