Over 200 people are killed each year when backed over by motor vehicles. The GranCabrio has standard Rear Emergency Braking that uses rear sensors to monitor for objects to the rear and automatically applies the brakes to prevent a collision. The 911 doesn’t offer automatic braking for stationary objects directly to the rear.
To provide maximum traction and stability on all roads, All-Wheel Drive is standard on the GranCabrio. But it costs extra on the 911.
The GranCabrio’s optional 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 911 doesn’t offer a driver alert monitor.
Both the GranCabrio and the 911 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, available lane departure warning systems, blind spot warning systems, around view monitors and rear cross-path warning.
The Maserati GranCabrio weighs 527 to 1094 pounds more than the Porsche 911. The NHTSA advises that heavier cars are much safer in collisions than their significantly lighter counterparts.

