The TTS blends the original Bauhaus styling with Audi's current modern design theme and advanced technology. The coupes spaceframe is 69% aluminum and 31% steel (roadster = 58/42%), with most of the steel in the rear to offset the weight of the engine and better balance the car. All TTS's are powered by a 265-hp turbocharged direct-injection 2.0-liter four-cylinder with a six-speed automatic S-tronic as the only transmission choice. The all-wheel drive quattro system has been customized specifically to the TTS for faster response time. Unique body treatments, 18" wheels and black brake calipers provide the visual differentiation from the TT. Safety features include front, side and knee airbags, run-flat tires with pressure monitoring and 4-wheel anti-lock brakes and stability control.