The federal government will propose rules, possibly as early as this week, to require oil companies to produce cleaner, less sulphurousgasoline and automakers to build light trucks and sports-utility vehicles with the same emissionsstandards as cars. The new requirements from the Environmental Protection Agency would be equivalent to removing 54 million polluting cars from the road. While the result would be cleaner air, the rules could also increase the price for gasoline, the popular pickup trucks and sports-utility vehicles (SUVs) -which now account for half of U.S. vehicle sales.