The GLS’ pre-crash front seatbelts will tighten automatically in the event the vehicle detects an impending crash, improving protection against injury significantly. The Highlander doesn’t offer pre-crash pretensioners.
To provide maximum traction and stability on all roads, All-Wheel Drive is standard on the GLS. But it costs extra on the Highlander.
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 Highlander doesn’t offer a system that can receive automated systems from other vehicles.
To help make backing out of a parking space safer, the GLS has standard Rear Cross-Traffic Alert with Active Brake Assist, systems which detect vehicles approaching from the sides and can automatically apply the brakes to prevent a collision. Only the Highlander Limited/Platinum offers Parking Support Brake.
Both the GLS and the Highlander 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, plastic fuel tanks, 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 1036 to 2065 pounds more than the Toyota Highlander. The NHTSA advises that heavier vehicles are much safer in collisions than their significantly lighter counterparts.

