The 8 Series’ pre-crash front seatbelts will tighten automatically in the event the vehicle detects an impending crash, improving protection against injury significantly. The 718 Cayman doesn’t offer pre-crash pretensioners.
The 8 Series 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 718 Cayman 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.
The 8 Series offers all-wheel drive to maximize traction under poor conditions, especially in ice and snow. The 718 Cayman doesn’t offer all-wheel drive.
The 8 Series’ lane departure warning system alerts a temporarily inattentive driver when the vehicle begins to leave its lane and gently nudges the vehicle back towards its lane. The 718 Cayman doesn’t offer a lane departure warning system.
To help make backing out of a parking space safer, the 8 Series’ 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 718 Cayman doesn’t offer a rear cross-path warning system.
The 8 Series’ 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 718 Cayman doesn’t offer a driver alert monitor.
Both the 8 Series and the 718 Cayman 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, daytime running lights, rearview cameras, available blind spot warning systems and rear parking sensors.
The BMW 8 Series weighs 626 to 1651 pounds more than the Porsche 718 Cayman. The NHTSA advises that heavier cars are much safer in collisions than their significantly lighter counterparts.