The X4’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 X4 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 X4 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.
To provide maximum traction and stability on all roads, All-Wheel Drive is standard on the X4. But it costs extra on the QX50.
The X4’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 X4 and the QX50 have standard driver and passenger frontal airbags, front 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 around view monitors.