AUBURN HILLS, MI – You shouldn't be surprised if the new A4, which debuts at this fall's Frankfurt Auto Show, looks a lot like its two-door brother, the A5. The A5, after all, is the car that its designer, Walter De'Silva, declared to be the most beautiful car he's ever designed. The A4 is a little less sexy, but the resemblance is clear — and their shared appearance isn't just skin-deep.

Audi doesn't like to call its new platform — B8 — a platform, instead describing it as a matrix. Either way, it's shared with the A5, which means that it uses Audi's new drivetrain layout that swaps the location of the differential and clutch. The new layout allows the engine to be moved further back in the chassis, and the results are measurable: compared to the current A4, the new car's front axle has been moved forward by 6.1 inches.

The resulting short front overhang removes some of the trademark Audi visual front-heaviness, giving a BMW-like stance. At 185.2 inches long, the A4 is a full seven inches longer than its Bavarian competition, the 3-series, and it rides on a wheelbase that is almost two inches longer. An even bigger difference is in the trunk size — the A4's enormous, 17 cu. ft. trunk dwarfs the BMW's, which can swallow only 12 cu. ft. of junk.

Not only is the new platform significantly bigger than the old A4's, it's more rigid. And, more impressively, it's ten percent lighter — the base, front-wheel drive A4 weighs only 3109 lb.

That model uses a 1.8L turbo unit that is closely related to the 2.0T in current U.S.-market Audis. It, like all of the engines in the new A4 lineup, uses direct injection. In 1.8L form, it produces 160 hp and 184 lb.-ft. of torque, and when equipped with a six-speed manual, it accelerates the A4 to 62 mph in 8.6 seconds. A Multitronic continuously variable transmission (CVT) is available as an option on front-wheel drive A4s.

The top-specification 3.2L V-6 sends its 265 hp and 243 lb.-ft. of torque to all four wheels using Audi's rear-biased Quattro system, and, with a manual 'box can hit 62 in 6.2 seconds. A six-speed automatic transmission is still under development for Quattro-equipped cars - the previous unit won't fit in the new chassis because of the new layout. The 3.2L uses Audi's AVS variable valve lift system, which helps improve fuel economy drastically: the new engine uses almost fifteen percent less fuel than the old one - which produced ten horsepower less.