Clean diesel or hybrid drive? It's an intriguing question, and one that's not quite so easy to answer. There's the price of diesel fuel to consider, which runs a few dimes over that of regular gasoline. Then there is fuel mileage. Does the Volkswagen Jetta TDI have a shot at dethroning the Toyota Prius as the undisputed mileage champion of the U.S.? To get a preliminary answer to some of these questions, Popular Mechanics put almost 500 miles on both cars, dividing up their miles between the city and the highway. It's not a knock-out for either car, but it may offer some early answers to a few questions.

First, the mileage. In the city, there's just no beating a hybrid, which uses its electric motor to good effect and scores over ten mpg better in the stop-and-go traffic of Los Angeles. On the highway, though, the Jetta TDI is able to eke out a narrow victory, scoring less than one mile per gallon better. Once the price of crude is factored in, the Prius remains the overall cheaper car to keep filled up. Of course, there is more to the story than that, including which car is a better to drive -- according to PM, the Jetta. Finally, the TDI qualifies for a $1,300 tax credit that the Prius can't claim. It's too close to call. Expect a rematch soon enough.

We recently received a note from an anonymous source indicating that there's a mildly strained relationship between VW and some of its dealers. The source of the consternation seems to be the highly anticipated Jetta TDI, which was just recently released in the U.S. market. Apparently, Volkswagen of America has gotten complaints that some dealers are adding a significant markup on the new and desirable model -- a big problem for many automakers when a new model makes its initial introduction. The dealers are eager to make some money on the new cars while VW is concerned that customers may just look elsewhere because they feel they're being treated unfairly. What's more, some VW dealers may not be all that excited by the new model as there aren't that many available quite yet.

This is a situation that's frustrating for the dealers, VW and, most importantly, prospective customers. Volkswagen promises that the situation will improve, and we hope it does. If the clean diesel engine is truly capable of returning the kind of fuel mileage that VW says it can, the Jetta TDI sedan and Sportwagen may indeed offer an ideal alternative to gasoline-sipping hybrids, that is, if customers can put up with the buying process.