Autos

Audi Q7 3.0 TDI

On sale: Early 2009

Fuel savings today, 15,000 miles: $1,201
Year-ago savings: $1,530
Difference: $329
Mileage: 25 mpg (combined, estimated)
Closest gas model: Audi Q7 3.6 FSI
Mileage: 16 mpg (combined city/highway)

The Audi Q7 3.0 TDI has a turbocharged, 240-hp, 3.0-liter, six-cylinder diesel engine. Audi has big plans for diesels in the U.S., now that low-sulfur diesel fuel and improved emissions technology make it possible to offer diesels in all 50 states. Diesel accounts for half of worldwide Audi sales, but not in the U.S. Besides the Q7 and the A4 (below), Audi will roll out more diesels starting in 2010. But fuel prices make for tough sledding. In the last year, rising diesel costs have eaten up about 20% of the annual fuel-cost advantage of better mileage.