The GLS’ pre-crash front seatbelts will tighten automatically in the event the vehicle detects an impending crash, improving protection against injury significantly. The MDX doesn’t offer pre-crash pretensioners.
The GLS 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 MDX 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.
To provide maximum traction and stability on all roads, All-Wheel Drive is standard on the GLS. But it costs extra on the MDX.
When descending a steep, off-road slope, the GLS’ standard Downhill Speed Regulation allows you to creep down safely. The MDX doesn’t offer Downhill Speed Regulation.
Earlier warning of stopped traffic, traffic signals, dangerous road conditions, weather, or accidents, can keep driver's safer and prevent crashes. The GLS has Car-to-X Communication, a system that seamlessly communicates important warnings to the driver about impending danger, if they're available. The MDX doesn’t offer a system that can receive automated systems from infrastructure or other vehicles.
Both the GLS and MDX have rear cross-traffic warning, but the GLS has Active Brake Assist (automatically applies the brakes) to better prevent a collision when backing near traffic. The MDX’s Rear Cross Traffic Monitor doesn’t automatically brake.
Both the GLS and the MDX have standard driver and passenger frontal airbags, front side-impact airbags, driver knee airbags, side-impact head airbags, front and rear seatbelt pretensioners, height adjustable front shoulder belts, four-wheel antilock brakes, traction control, electronic stability systems to prevent skidding, crash mitigating brakes, daytime running lights, lane departure warning systems, blind spot warning systems, rearview cameras, rear cross-path warning and driver alert monitors.
The Mercedes GLS weighs 769 to 1952 pounds more than the Acura MDX. The NHTSA advises that heavier vehicles are much safer in collisions than their significantly lighter counterparts.