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 McLaren GTS doesn't offer collision warning or crash mitigation brakes.
Over 200 people are killed each year when backed over by motor vehicles. The 911 (except Manual/GT3) offers an optional Maneuvering Assist that uses rear sensors to monitor for objects to the rear and automatically applies the brakes to prevent a collision. The McLaren GTS doesn’t offer backup collision prevention brakes.
The 911 offers all-wheel drive to maximize traction under poor conditions, especially in ice and snow. The McLaren GTS 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 McLaren GTS doesn’t offer a night vision system.
The 911’s 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 McLaren GTS 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 McLaren GTS 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 McLaren GTS 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 McLaren GTS doesn’t offer a rear cross-path warning system.
The 911’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 McLaren GTS doesn’t offer a driver alert monitor.
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 McLaren GTS 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 McLaren GTS 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 and rearview cameras.

