For enhanced safety, the front and middle seat shoulder belts of the Volvo XC90 are height-adjustable to accommodate a wide variety of driver and passenger heights. A better fit can prevent injuries and the increased comfort also encourages passengers to buckle up. The Mercedes GLS doesn’t offer height-adjustable middle seat belts.
Both the XC90 and GLS have child safety locks to prevent children from opening the rear doors. The XC90 has power child safety locks, allowing the driver to activate and deactivate them from the driver's seat and to know when they're engaged. The GLS’ child locks have to be individually engaged at each rear door with a manual switch. The driver can’t know the status of the locks without opening the doors and checking them.
The Volvo XC90 offers an optional built in child booster seat. It’s more crash worthy than an added child seat because of its direct attachment to the seat. Mercedes doesn’t offer the convenience and security of a built-in child booster seat in the GLS. Their owners must carry a heavy booster seat in and out of the vehicle; XC90 owners can just fold their built-in child seat up or down.
Using vehicle speed sensors and seat sensors, smart airbags in the XC90 deploy with different levels of force or don’t deploy at all to help better protect passengers of all sizes in different collisions. The XC90’s side airbags will shut off if a child is leaning against the door. The GLS’ side airbags don’t have smart features and will always deploy full force.
The XC90 has a standard Whiplash Protection System (WHIPS), which use a specially designed seat to protect the driver and front passenger from whiplash. During a rear-end collision, the WHIPS allows the backrest to travel backwards to cushion the occupants and the headrests move forward to prevent neck and spine injuries. At the same time the pretensioning seatbelts fire, removing slack from the belts. The GLS doesn’t offer a whiplash protection system.
The XC90 has standard Post-impact braking, which automatically apply the brakes in the event of a crash to help prevent secondary collisions and prevent further injuries. The GLS 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 XC90 has standard CTA Auto Brake that uses rear sensors to monitor and automatically apply the brakes to prevent a rear collision. The GLS doesn’t offer backup collision prevention brakes.
The XC90’s standard lane departure warning system alerts a temporarily inattentive driver when the vehicle begins to leave its lane and gently nudges the vehicle back towards its lane. A lane departure warning system costs extra on the GLS.
Both the XC90 and the GLS 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, all wheel drive, traction control, electronic stability systems to prevent skidding, crash mitigating brakes, daytime running lights, blind spot warning systems, rearview cameras, rear cross-path warning, driver alert monitors and available around view monitors.
For its top level performance in IIHS driver and passenger-side small overlap frontal, moderate overlap frontal, side impact, roof strength and head restraint tests, its standard vehicle-to-vehicle front crash prevention system, its standard vehicle-to-pedestrian front crash prevention system, and its standard headlight’s “Acceptable” rating, the Insurance Institute for Highway Safety grants the XC90 its highest rating: “Top Safety Pick Plus” for 2022, a rating granted to only 95 vehicles tested by the IIHS. The GLS has not been tested, yet.