The gauntlet is thrown: VW Jetta TDI vs. Toyota Priu

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.