The TTS blends the original Bauhaus styling with Audi's current modern design theme and advanced technology. The coupe's 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, 19-inch 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. For 2011, the TTS receives a mid-lifecycle update that includes new front grilles, standard 19-inch wheels, new colors and interior trim upgrades.