The Spectre’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 Quattroporte doesn’t offer a driver alert monitor.
Both the Spectre and the Quattroporte have standard driver and passenger frontal airbags, four-wheel antilock brakes, all wheel drive, traction control, electronic stability systems to prevent skidding, crash mitigating brakes, lane departure warning systems, blind spot warning systems, around view monitors and rear cross-path warning.
The Rolls-Royce Spectre weighs 2210 pounds more than the Maserati Quattroporte. The NHTSA advises that heavier cars are much safer in collisions than their significantly lighter counterparts.

