As of Monday, May 11th, the average price for a gallon of diesel fuel in the U.S. was $2.216, while the average price for a gallon of regular-grade gasoline was $2.240. That's a big deal, as diesel fuel has historically cost a least a bit more than premium gasoline here in the United States. Obviously, that trend is slowly changing. Towards the end of March, there were many areas of the country where diesel fuel was less expensive than gasoline, and today, that trend has taken hold on a national level.

Although this may seem like excellent news for automakers interested in selling diesel vehicles in the States, it has pretty much proven impossible to accurately predict what fuel prices will be more than a few weeks in advance. So, while it may seem likely that automakers would be more willing to bring efficient oil-burning cars to the American market in light of these favorable diesel prices, we wouldn't recommend getting your hopes up. However, if you already own a whirling derv, you may just have enough extra scratch at the end of the week to get yourself that cup of Starbucks.

[Source: Energy Information Administration]