The X5’s pre-crash front seatbelts will tighten automatically in the event the vehicle detects an impending crash, improving protection against injury significantly. The QX50 doesn’t offer pre-crash pretensioners.
The X5 has standard Active Head Restraints, which use a specially designed headrest to protect the driver and front passenger from whiplash. During a rear-end collision, the Active Head Restraints system moves the headrests forward to prevent neck and spine injuries. The QX50 doesn’t offer a whiplash protection system.
The X5 has a standard PostCrash iBrake, which automatically applies the brakes in the event of a crash to help prevent secondary collisions and prevent further injuries. The QX50 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.
When descending a steep, off-road slope, the X5’s standard Hill Descent Control allows you to creep down safely. The QX50 doesn’t offer Hill Descent Control.
Both the X5 and QX50 have rear cross-traffic warning, but the X5 has Cross Traffic Warning with Braking (automatically applies the brakes) to better prevent a collision when backing near traffic. The QX50’s Rear Cross Traffic Alert doesn’t automatically brake.
The X5’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 QX50 doesn’t offer a driver alert monitor.
Both the X5 and the QX50 have standard driver and passenger frontal airbags, front and rear side-impact airbags, driver and front passenger knee airbags, side-impact head airbags, front seatbelt pretensioners, 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 available all wheel drive.
The BMW X5 weighs 739 to 1724 pounds more than the Infiniti QX50. The NHTSA advises that heavier vehicles are much safer in collisions than their significantly lighter counterparts.