For enhanced safety, the front seat shoulder belts of the Audi A3 are height-adjustable to accommodate a wide variety of driver and passenger heights. A better fit can prevent injuries and the increased comfort also encourages passengers to buckle up. The BMW 3 Series Sedan doesn’t offer height-adjustable seat belts.
Both the A3 and 3 Series Sedan have child safety locks to prevent children from opening the rear doors. The A3 has power child safety locks, allowing the driver to activate and deactivate them from the driver's seat and to know when they're engaged. The 3 Series Sedan’s child locks have to be individually engaged at each rear door with a manual switch. The driver can’t know the status of the locks without opening the doors and checking them.
To provide maximum traction and stability on all roads, All-Wheel Drive is standard on the A3. But it costs extra on the 3 Series Sedan.
The A3 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 3 Series Sedan’s blind spot costs extra.
To help make backing out of a parking space safer, the A3 has standard Rear Cross-Traffic Assist and Automatic Brake Activation automatically engages the brakes to help avoid a collision. BMW charges extra for Cross Traffic Warning on the 3 Series Sedan and the 3 Series Sedan’s Cross Traffic Warning does not include automatic braking.
Both the A3 and the 3 Series Sedan have standard driver and passenger frontal airbags, front side-impact airbags, driver and front passenger knee airbags, side-impact head airbags, front seatbelt pretensioners, four-wheel antilock brakes, traction control, electronic stability systems to prevent skidding, crash mitigating brakes, post-collision automatic braking systems, daytime running lights, lane departure warning systems, rearview cameras and available around view monitors.