The 911 (except GT3) has standard Warn and Brake Assist, which use forward mounted sensors to warn the driver of a possible collision ahead. If the driver doesn’t react and the system determines a collision is imminent, it automatically applies the brakes at full-force in order to reduce the force of the crash or avoid it altogether. The R8 doesn't offer collision warning or crash mitigation brakes.
A passive infrared night vision system optional on the 911 helps the driver to more easily detect people, animals or other objects in front of the vehicle at night. Using an infrared camera to detect heat, the system then displays the image on a monitor in the dashboard. The R8 doesn’t offer a night vision system.
The 911’s optional 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 R8 doesn’t offer a lane departure warning system.
The 911 offers an optional Surround View to allow the driver to see objects all around the vehicle on a screen. The R8 only offers a rear monitor and front and rear parking sensors that beep or flash a light. That doesn’t help with obstacles to the sides.
The 911’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. The R8 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 911’s optional Rear Cross Traffic Alert uses sensors in the rear to alert the driver to vehicles approaching from the side and automatically engage the brakes. The R8 doesn’t offer a rear cross-path warning system.
Both the 911 and the R8 have standard driver and passenger frontal airbags, front side-impact 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 and available all wheel drive.