The 50 Quattro produces 308 h.p. from 2 electric motors and a 71 kW.h. battery pack providing a range of 215 miles (347 km). The E-Tron Sportback 55 Quattro makes 355hp from a 95 kWh capacity battery and is capable of producing 402hp for 8 seconds in boost mode, with a range of 277 miles (445 km). For regular driving the E-Tron Sportback uses only the rear electric motor for better efficiency, the front unit engages when the driver requires more power or when it detects a loss of grip.