In the past twenty years hundreds of infants and young children have died after being left in vehicles, usually by accident. When turning the vehicle off, drivers of the Sentra are reminded to check the back seat if they opened the rear door before starting out. The A3 doesn’t offer a back seat reminder.
Over 200 people are killed each year when backed over by motor vehicles. The Sentra has standard Rear Automatic Braking that uses rear sensors to monitor for objects to the rear and automatically applies the brakes to prevent a collision. The A3 doesn’t offer automatic braking for stationary objects directly to the rear.
The Sentra SV/SR offers an optional Around View® Monitor to allow the driver to see objects all around the vehicle on a screen. The A3 only offers a rear monitor and front and rear parking sensors that beep or flash a light. That doesn’t help with obstacles to the sides.
The Sentra has a standard blind spot warning system that uses sensors to alert the driver to objects in the vehicle’s blind spots where the side view mirrors don’t reveal them. A system to reveal vehicles in the A3’s blind spot costs extra.
To help make backing out of a parking space safer, the Sentra has standard Rear Cross Traffic Alert, helping the driver avoid collisions. Audi charges extra for Rear Cross-Traffic Assist on the A3.
The Sentra’s driver alert monitor detects an inattentive driver then sounds a warning and suggests a break. According to the NHTSA, drivers who fall asleep cause about 100,000 crashes and 1500 deaths a year. The A3 doesn’t offer a driver alert monitor.
Both the Sentra and the A3 have standard driver and passenger frontal airbags, front and rear side-impact airbags, driver and front passenger knee airbags, side-impact head airbags, front seatbelt pretensioners, front wheel drive, height adjustable front shoulder belts, four-wheel antilock brakes, traction control, electronic stability systems to prevent skidding, crash mitigating brakes, lane departure warning systems, rearview cameras and available daytime running lights.