Over 200 people are killed each year when backed over by motor vehicles. The Q50 (except 2.0t) offers optional Back-up Collision Intervention that uses rear sensors to monitor and automatically apply the brakes to prevent a rear collision. The A3 Sedan doesn’t offer backup collision prevention brakes. INFINITI’s powertrain warranty covers the Q50 2 years and 20,000 miles longer than Audi covers the A3 Sedan. Any repair needed on the engine, transmission, axles, joints or driveshafts is fully covered for 6 years or 70,000 miles. Coverage on the A3 Sedan ends after only 4 years or 50,000 miles. In heavy traffic or at stoplights the Q50 2.0t’s engine automatically turns off when the vehicle is stopped, saving fuel and reducing pollution. The engine is automatically restarted when the driver gets ready to move again. (Start/Stop isn’t accounted in present EPA fuel mileage tests.) The A3 Sedan doesn’t offer an automatic engine start/stop system.