(SOUNDBITE OF ENGINE REVVING)
AILSA CHANG, HOST:
Oh, yes, music to the ears of gearheads everywhere - a diesel automobile roaring down a highway. It's a sound more likely to be heard in Europe than in the U.S. Over here, we burn gasoline, and a large percentage of our passenger vehicles and light trucks always have. And here's why.
ARI SHAPIRO, HOST:
Habit has a lot to do with it - also diesel's reputation for noise and smoke. The Department of Energy's John Maples says it also has to do with emissions policies set in the 1990s in Europe.
JOHN MAPLES: They've had a more relaxed standard to meet than the gasoline vehicles. And then the emissions standards in the United States are for all vehicles. They're not fuel specific.
SHAPIRO: That means here in the U.S., diesel vehicles have to hit the same emissions standards as gasoline vehicles, which is not easy. And back in the '70s when U.S. automakers rolled out a line of diesel-powered cars, the whole thing was a little halfhearted.
MAPLES: They were converted engines that were previously gasoline engines for the U.S. products, and they didn't perform particularly well.
CHANG: And that's why you rarely hear this sound on America's highways.
(SOUNDBITE OF ENGINE REVVING) Transcript provided by NPR, Copyright NPR.