2010 Audi A3 2.0 TDI at 2009 Detroit Auto Show

• Competes with: Mini Cooper, Volvo C30
• Looks like: Your everyday A3 hatchback
• Drivetrain: 140-hp, turbocharged 2.0-liter four-cylinder diesel engine with six-speed automatic; front-wheel drive
• Hits dealerships: First quarter of 2010

German luxury automakers Audi, BMW and Mercedes-Benz have all been announcing diesel-powered models for the U.S., but many of the models getting diesel engines have been larger cars and SUVs. Now, Audi has added a diesel engine to its smallest model for 2010: the A3 2.0 TDI.

The A3 2.0 TDI hatchback is powered by a turbocharged, 2.0-liter four-cylinder diesel engine that uses common-rail direct injection. It makes 140 hp, but as is customary with diesels it produces a whopping amount of torque; the diesel is rated at 236 pounds-feet, which is nearly as much as Audi’s 3.2-liter V-6 gas engine produces. The diesel pairs with Audi’s S tronic dual-clutch automatic transmission.

Official fuel-economy figures haven’t been released, but Audi says the A3 2.0 TDI should get more than 40 mpg on the highway. Pricing hasn’t been announced either, but Audi says it will be released around the time the car goes on sale in the first quarter of next year.

As long as the cost of diesel fuel stays higher than gasoline — lessening the economic impact of a diesel engine’s efficiency gains — it’s going to be difficult to get buyers to consider diesel cars and their expensive engine technology when gasoline equivalents are available. As we saw in 2008, however, fuel prices can change rapidly over a short period of time, and the market could be quite different a year from now when the A3 2.0 TDI hits dealerships.More photos below.