Europe's known it for years ... diesel engine vehicles deliver a far superior level of fuel economy. Year-after-year, Volkswagen and Mercedes-Benz continue to sell their diesel offerings to a crazed cult of Americans. Environmental regulations have changed the formulation of diesel fuel and the automakers have scrambled to bring ever-cleaner diesels stateside.

While Mercedes-Benz continued to offer diesel engines in the 2007 model year, Volkswagen took a year off to gear up with a new diesel powerplant for the Jetta. Mercedes-Benz takes the Best Gas Mileage Diesel and Best Gas Mileage Luxury Sedan crowns with the six-cylinder E320 Bluetec.

Jeep was the only American automaker to offer a diesel engine in anything other than a full-fledged truck. The diesel-equipped Jeep Grand Cherokee struggled to reach mileage comparable to the 4WD Mercedes-Benz 320s.

The ten-cylinder Volkswagen Touareg is a diesel horse of a different color. Sharing underpinnings with the Porsche Cayenne, the Touareg isn't focused on high-MPG, rather than the ooomph: monster torque and horsepower.

Model	Engine	Displacement	Transmission	Fuel	City	Highway
Mercedes-Benz E320 Bluetec	6 cylinder	3 liter	Automatic (L7)	Diesel	23 city	32 highway
Mercedes-Benz R320 CDI 4matic	6 cylinder	3 liter	Automatic (L7)	Diesel	19 city	26 highway
Mercedes-Benz ML320 CDI 4matic	6 cylinder	3 liter	Automatic (L7)	Diesel	19 city	24 highway
Jeep Grand Cherokee 2WD	6 cylinder	3 liter	Automatic (5)	Diesel	18 city	23 highway
Mercedes-Benz GL320 CDI 4matic	6 cylinder	3 liter	Automatic (L7)	Diesel	18 city	23 highway
Jeep Grand Cherokee 4WD	6 cylinder	3 liter	Automatic (5)	Diesel	17 city	22 highway
Volkswagen Touareg	10 cylinder	5 liter	Automatic (6)	Diesel	15 city	20 highway