The Audi A3 is a bit of an odd duck in Audi's U.S. lineup, mainly because it's only available in a four-door hatch format here. That's about to change with the reveal of the Audi A3 concept, a sedan-based vision of the next-generation car that's making its world debut at the 2011 Geneva auto show. The concept is strikingly similar in form to the now-legendary B5 S4, a car that changed the way people think about performance sedans.
All the dimensions of the new A3 Concept match up to the old B5, with length, width, and height within a couple of inches. The good news: The new A3 is apparently a few hundred pounds lighter, weighing just south of 3400 lbs. Audi saved weight by building the doors, hood, and trunklid out of aluminum. The unibody is apparently still formed out of steel, since this is an entry-level car, but the floor panel varies in thickness and has been optimized for strength. Audi also claims it is using new joining methods for the unibody, but didn't go into more detail.
The drivetrain for the A3 is classic Audi that even predates the B5. Under the aluminum hood is a 2.5-liter turbo direct-injection inline five-cylinder tuned to sound like the rally cars of the 1980s. Although it is far more efficient and cleaner than the road-going versions of the old five-cylinders, it produces power similar to the racing engines. The FSI engine, also found in the TT-RS, is tuned to produce 408 horsepower and 369 pound-feet of torque from 1600 RPM all the way to 5300 RPM. And it does all this while delivering 26 mpg in the European urban cycle.