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 Prius Prime doesn’t offer pre-crash pretensioners.
Both the S90 and Prius Prime 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 Prius Prime’s 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. Toyota doesn’t offer the convenience and security of a built-in child booster seat in the Prius Prime. 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 Volvo S90 has a standard driver’s side knee airbag mounted low on the dashboard. The knee airbag helps prevent the driver from sliding under the seatbelts or the main frontal airbag; this keeps the driver better positioned during a collision for maximum protection. A knee airbag also helps keep the legs from striking the dashboard, preventing knee and leg injuries in the case of a serious frontal collision. The Prius Prime doesn’t offer knee airbags.
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 Prius Prime doesn’t offer a whiplash protection system.
The S90 has all-wheel drive to maximize traction under poor conditions, especially in ice and snow. The Prius Prime doesn’t offer all-wheel drive.
Both the S90 and the Prius Prime have standard driver and passenger frontal airbags, front and rear side-impact 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 725 to 1212 pounds more than the Toyota Prius Prime. The NHTSA advises that heavier cars are much safer in collisions than their significantly lighter counterparts.
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 S90 its highest rating: “Top Safety Pick Plus” for 2022, a rating granted to only 128 vehicles tested by the IIHS. The Prius Prime has not been tested, yet.