Currently automakers have to meet an average fuel economy standard of 21 miles per gallon for their entire consumer truck fleet, which includes all sizes of trucks from small to large, as well as SUVs and vans. The Bush administration is proposing a new multi-tiered standard based on the size of a truck and not its weight. Developed by the National Highway Traffic Safety Administration, the new proposal would group trucks in categories with different fuel economy standards. Light trucks, for instance, would have a stricter fuel economy standard than larger ones. The current sales-weighted standard creates problems for the domestic automakers, each of which sells significantly more large, less fuel efficient trucks than they do smaller ones. This is, perhaps, one reason why the domestics would like to introduce hybrid powertrains into pickups and SUVs before passenger cars.