For enhanced safety, the front and rear seat shoulder belts of the Mercedes GLA have pretensioners to tighten the seatbelts and eliminate dangerous slack in the event of a collision and force limiters to limit the pressure the belts will exert on the passengers. The GMC Terrain doesn’t offer pretensioners for its rear seat belts.
The GLA’s pre-crash front seatbelts will tighten automatically in the event the vehicle detects an impending crash, improving protection against injury significantly. The Terrain doesn’t offer pre-crash pretensioners.
The Mercedes GLA has a standard driver’s side knee airbag mounted low on the dashboard. The knee airbag helps prevent the driver from sliding under the seatbelts or the main frontal airbag; this keeps the driver better positioned during a collision for maximum protection. A knee airbag also helps keep the legs from striking the dashboard, preventing knee and leg injuries in the case of a serious frontal collision. The Terrain doesn’t offer knee airbags.
The GLA’s standard pretensioning seatbelts also sense rear collisions and remove slack from the seatbelts to help protect the occupants from whiplash and other injuries. The Terrain doesn’t offer a whiplash protection system.
The GLA offers an optional Post Collision Brake, which automatically applies the brakes in the event of a crash to help prevent secondary collisions and prevent further injuries. The Terrain 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.
The GLA 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 Terrain’s blind spot costs extra.
To help make backing out of a parking space safer, the GLA has standard Rear Cross-Traffic Alert and Active Brake Assist automatically engages the brakes to help avoid a collision. GMC charges extra for Rear Cross Traffic Alert on the Terrain and the Terrain’s Rear Cross Traffic Alert does not include automatic braking.
The GLA’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 Terrain doesn’t offer a driver alert monitor.
Both the GLA and the Terrain have standard driver and passenger frontal airbags, front side-impact airbags, side-impact head airbags, front wheel drive, four-wheel antilock brakes, traction control, electronic stability systems to prevent skidding, crash mitigating brakes, daytime running lights, rearview cameras, available all wheel drive, lane departure warning systems and around view monitors.