The S90’s pre-crash front seatbelts will tighten automatically in the event the vehicle detects an impending crash, improving protection against injury significantly. The ES doesn’t offer pre-crash pretensioners.
Both the S90 and ES have child safety locks to prevent children from opening the rear doors. The S90 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 ES’ 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 S90 offers optional built in child booster seats. They’re more crash worthy than an added child seat because of their direct attachment to the seat. Lexus doesn’t offer the convenience and security of a built-in child booster seat in the ES. Their owners must carry a heavy booster seat in and out of the vehicle; S90 owners can just fold their built-in child seat up or down.
The S90 has a standard Whiplash Protection System (WHIPS), which use a specially designed headrest to protect the driver and front passenger from whiplash. During a rear-end collision, the WHIPS moves the headrests forward to prevent neck and spine injuries. At the same time the pretensioning seatbelts fire, removing slack from the belts. The ES doesn’t offer a whiplash protection system.
To provide maximum traction and stability on all roads, All-Wheel Drive is standard on the S90. But it costs extra on the ES.
Both the S90 and the ES have standard driver and passenger frontal airbags, front and rear 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, post-collision automatic braking systems, daytime running lights, lane departure warning systems, blind spot warning systems, rearview cameras, rear cross-path warning and driver alert monitors.
The Volvo S90 weighs 516 to 983 pounds more than the Lexus ES. The NHTSA advises that heavier cars are much safer in collisions than their significantly lighter counterparts.