The Z4’s pre-crash front seatbelts will tighten automatically in the event the vehicle detects an impending crash, improving protection against injury significantly. The Cooper Convertible doesn’t offer pre-crash pretensioners.
Over 200 people are killed each year when backed over by motor vehicles. The Z4 (except Manual) offers an optional Active Park Distance Control that uses rear sensors to monitor for objects to the rear and automatically applies the brakes to prevent a collision. The Cooper Convertible doesn’t offer backup collision prevention brakes.
The Z4’s optional blind spot warning system uses sensors to alert the driver to objects in the vehicle’s blind spots where the side view mirrors don’t reveal them and moves the vehicle back into its lane. The Cooper Convertible doesn’t offer a system to reveal objects in the driver’s blind spots.
To help make backing out of a parking space safer, the Z4’s optional Cross Traffic Warning uses sensors in the rear to alert the driver to vehicles approaching from the side, helping the driver avoid collisions. The Cooper Convertible doesn’t offer a rear cross-path warning system.
Both the Z4 and the Cooper Convertible have standard driver and passenger frontal airbags, front side-impact airbags, driver and front passenger knee airbags, side-impact head airbags, front seatbelt pretensioners, four-wheel antilock brakes, traction control, electronic stability systems to prevent skidding, crash mitigating brakes, post-collision automatic braking systems, daytime running lights, rearview cameras, driver alert monitors, available lane departure warning systems and rear parking sensors.

