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 812 doesn't offer collision warning or crash mitigation brakes.
The 911 offers all-wheel drive to maximize traction under poor conditions, especially in ice and snow. The 812 doesn’t offer all-wheel drive.
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 812 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 812 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 812 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 has standard Porsche Connect, which uses a global positioning satellite (GPS) receiver and a cellular system to remotely unlock your doors if you lock your keys in, help track down your vehicle if it’s stolen or send emergency personnel to the scene if any airbags deploy. The 812 doesn’t offer a GPS response system, only a navigation computer with no live response for emergencies, so if you’re involved in an accident and you’re incapacitated help may not come as quickly.
Both the 911 and the 812 have standard driver and passenger frontal airbags, side-impact head airbags, front seatbelt pretensioners, four-wheel antilock brakes, traction control, electronic stability systems to prevent skidding, daytime running lights, rear parking sensors and available blind spot warning systems.