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 Quattroporte doesn’t offer pre-crash pretensioners.
Both the S90 and Quattroporte 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 Quattroporte’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. Maserati doesn’t offer the convenience and security of a built-in child booster seat in the Quattroporte. 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 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 Quattroporte 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 S90 has standard CTA Auto Brake that uses rear sensors to monitor for objects to the rear and automatically applies the brakes to prevent a collision. The Quattroporte doesn’t offer backup collision prevention brakes.
Both the S90 and Quattroporte have rear cross-traffic warning, but the S90 has Braking Intervention (automatically applies the brakes) to better prevent a collision when backing near traffic. The Quattroporte’s Rear Cross Path doesn’t automatically brake.
The S90’s driver alert monitor detects an inattentive driver then sounds a warning and suggests a break. According to the NHTSA, drivers who fall asleep cause about 100,000 crashes and 1500 deaths a year. The Quattroporte doesn’t offer a driver alert monitor.
Both the S90 and the Quattroporte 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, all wheel drive, traction control, electronic stability systems to prevent skidding, crash mitigating brakes, daytime running lights, lane departure warning systems, blind spot warning systems, around view monitors and rear cross-path warning.
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 131 vehicles tested by the IIHS. The Quattroporte has not been tested, yet.