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 Chevrolet Trailblazer 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 Trailblazer doesn’t offer pre-crash pretensioners.
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 Trailblazer 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 Trailblazer 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 offers an optional Surround View System to allow the driver to see objects all around the vehicle on a screen. The Trailblazer only offers a rear monitor and rear parking sensors that beep or flash a light. That doesn’t help with obstacles to the front or sides.
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 Trailblazer’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. Chevrolet charges extra for Rear Cross Traffic Alert on the Trailblazer and the Trailblazer’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 Trailblazer doesn’t offer a driver alert monitor.
Both the GLA and the Trailblazer have standard driver and passenger frontal airbags, front side-impact airbags, driver knee 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 and lane departure warning systems.

