Perhaps the ìproblemî is wealth

Automakers have made no progress in improving vehicle fuel economy over the past year, continuing a nearly 25-year trend of industry stagnation on gasoline mileage, according to the Environmental Protection Agency. In an annual report released [recently], the EPA said the industry-wide fuel economy of 2006 model-year vehicles was 21 miles per gallon, the same as the year-ago level. Detroit automakers trailed their fast-growing Japanese, Korean and European counterparts, the report found … Gloria Bergquist, a spokeswoman for the Alliance of Automobile Manufacturers, which represents many of the automakers, said the industry is building more vehicles with fuel-saving technology, but consumers are still buying heavier, faster vehicles in large numbers. “The fuel-efficient models are out there, we just need to sell more,” she said. “We are trying very hard.”

Article here. Fuel efficiency jumped rather dramatically during the 70s and early 80s, during tough economic times. Today, despite all the griping about fuel prices, the dough we dump into our autos represents a smaller slice of our income than it used to.