At the 2011 Frankfurt Auto Show, Audi presented the Audi S7. This high performance version of the A7 features a 4.0 biturbo TFSI engine of 420 PS (309 kW; 414 bhp) and is offered only with the quattro four wheel drive system. Because of the 7 speed S Tronic gearbox, the maximum torque has been limited to 550 N·m (410 ft·lbf). The Audi S7 can do a 0-100 km/h (62 mph) acceleration in 4.9 seconds. A number of technologies contribute to this top result, including the recuperation and start-stop systems as well as the new “cylinder on demand” cylinder management system. When the V8 deactivates four cylinders under part load, the Active Noise Cancellation system (ANC) is activated. Four microphones integrated into the headlining record the noise in the cabin, which is then analyzed by a computer. If the computer detects intrusive sound elements, it broadcasts an antiphase sound through the speakers of the sound system. This sound combines with the intrusive sound and largely cancels it out.