Mercedes Benz E320 Bluetec

EPA fuel economy, city/highway: 27/37 (mfr's est)

There's a reason Mercedes places a BlueTec badge on the back of E320s and nothing that includes the word "diesel"—the company is trying to purge our collective mind of softly contoured Mercedes rattling their way to 60 mph in 24.7 seconds while inking the width of freeways with putrid oil smoke. And Mercedes is right to do so, because the new 3.0-liter V-6 mill is, according to the company, the "world's cleanest diesel, " packing more emissions-technology jargon than a coal-gasification plant. Using a variable-geometry turbocharger, four-valve heads, and third-generation common-rail direct injection, it also produces 400 lb-ft of torque between 1600 and 2400 rpm and accelerates only slightly less rapidly than its gasoline-powered E350 sibling. Fuel consumption: 37 mpg on the highway, two ticks better than the hybrid Honda Accord, and 27 mpg around town.