The M5 has a standard blind spot warning system that uses sensors to alert the driver to objects in the vehicle’s blind spots where the side view mirrors don’t reveal them and moves the vehicle back into its lane. A system to reveal vehicles in the RS 6’s blind spot costs extra.
To help make backing out of a parking space safer, the M5 has standard Cross Traffic Warning, helping the driver avoid collisions. Audi charges extra for Rear Cross-Traffic Assist on the RS 6.
Both the M5 and the RS 6 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, all wheel drive, traction control, electronic stability systems to prevent skidding, crash mitigating brakes, post-collision automatic braking systems, daytime running lights, lane departure warning systems, rearview cameras and driver alert monitors.
The BMW M5 weighs 408 to 548 pounds more than the Audi RS 6. The NHTSA advises that heavier cars are much safer in collisions than their significantly lighter counterparts.

