The AMG SL’s pre-crash front seatbelts will tighten automatically in the event the vehicle detects an impending crash, improving protection against injury significantly. The 720S doesn’t offer pre-crash pretensioners.
The AMG SL’s standard pretensioning seatbelts also sense rear collisions and remove slack from the seatbelts to help protect the occupants from whiplash and other injuries. The 720S doesn’t offer a whiplash protection system.
The AMG SL has standard Active 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 720S doesn't offer collision warning or crash mitigation brakes.
The AMG SL offers an optional Post Collision Brake, which automatically applies the brakes in the event of a crash to help prevent secondary collisions and prevent further injuries. The 720S 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.
Over 200 people are killed each year when backed over by motor vehicles. The AMG SL has a standard Maneuvering Brake that uses rear sensors to monitor for objects to the rear and automatically applies the brakes to prevent a collision. The 720S doesn’t offer backup collision prevention brakes.
The AMG SL has all-wheel drive to maximize traction under poor conditions, especially in ice and snow. The 720S doesn’t offer all-wheel drive.
The AMG SL’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 720S doesn’t offer a lane departure warning system.
The AMG SL’s 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 720S 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 AMG SL’s standard Rear Cross-Traffic Alert uses sensors in the rear to alert the driver to vehicles approaching from the side and Rear Cross Traffic Brake automatically engages the brakes to help avoid a collision. The 720S doesn’t offer a rear cross-path warning system.
The AMG SL’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 720S doesn’t offer a driver alert monitor.
The AMG SL has standard Mercedes-Benz Emergency Call, 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 720S 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 AMG SL and the 720S 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 and rearview cameras.
The Mercedes AMG SL weighs 1058 to 1166 pounds more than the McLaren 720S. The NHTSA advises that heavier cars are much safer in collisions than their significantly lighter counterparts.