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 3 Series Sedan are reminded to check the back seat if they opened the rear door before starting out. The A-Class doesn’t offer a back seat reminder.
The 3 Series Sedan has standard Active Head Restraints, which use a specially designed headrest to protect the driver and front passenger from whiplash. During a rear-end collision, the Active Head Restraints system moves the headrests forward to prevent neck and spine injuries. The A-Class doesn’t offer a whiplash protection system.
The 3 Series Sedan has a standard PostCrash iBrake, which automatically applies the brakes in the event of a crash to help prevent secondary collisions and prevent further injuries. The A-Class doesn’t offer a post collision braking system: in the event of a collision that triggers the airbags, more collisions are possible without the protection of airbags that may have already deployed.
Over 200 people are killed each year when backed over by motor vehicles. The 3 Series Sedan offers an optional Active Park Distance Control that uses rear sensors to monitor for objects to the rear and automatically applies the brakes to prevent a collision. The A-Class doesn’t offer backup collision prevention brakes.
To help make backing out of a parking space safer, the 3 Series Sedan’s optional Cross Traffic Warning uses sensors in the rear to alert the driver to vehicles approaching from the side, helping the driver avoid collisions. The A-Class doesn’t offer a rear cross-path warning system.
Both the 3 Series Sedan and the A-Class 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, daytime running lights, rearview cameras, driver alert monitors, available all wheel drive, lane departure warning systems, blind spot warning systems and around view monitors.
For its top level performance in all IIHS frontal, side, rear impact and roof-crush tests, and its standard front crash prevention system, the Insurance Institute for Highway Safety grants the 3 Series Sedan the rating of “Top Safety Pick” for 2017, a rating granted to only 231 vehicles tested by the IIHS. The A-Class has not been tested, yet.