The BMW X4 has standard driver and front passenger side knee airbags mounted low on the dashboard. These airbags helps prevent the driver and front passenger from sliding under their seatbelts or the main frontal airbags; this keeps them better positioned during a collision for maximum protection. Knee airbags also help keep the legs from striking the dashboard, preventing knee and leg injuries in the case of a serious frontal collision. The Acadia doesn’t offer a front passenger side knee airbag.
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 Acadia 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 Acadia 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 X4 offers optional Active Park Distance Control that uses rear sensors to monitor and automatically apply the brakes to prevent a rear collision. The Acadia doesn’t offer backup collision prevention brakes.
To provide maximum traction and stability on all roads, All-Wheel Drive is standard on the X4. But it costs extra on the Acadia.
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 Acadia doesn’t offer a driver alert monitor.
Both the X4 and the Acadia have standard driver and passenger frontal airbags, front side-impact airbags, driver 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.