For enhanced safety, the front and rear seat shoulder belts of the Audi S5 have pretensioners to tighten the seatbelts and eliminate dangerous slack in the event of a collision and force limiters to limit the pressure the belts will exert on the passengers. The BMW 8 Series doesn’t offer pretensioners for the rear seat belts.
To provide maximum traction and stability on all roads, All-Wheel Drive is standard on the S5. But it costs extra on the 8 Series.
When descending a steep, off-road slope, the S5’s standard Hill Descent Control allows you to creep down safely. The 8 Series doesn’t offer Hill Descent Control.
The S5 Premium Plus/Prestige has a standard Top View Cameras to allow the driver to see objects all around the vehicle on a screen. The 8 Series 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.
Both the S5 and the 8 Series have standard driver and passenger frontal airbags, front side-impact airbags, driver and front passenger knee airbags, side-impact head airbags, plastic fuel tanks, four-wheel antilock brakes, 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, available blind spot warning systems and rear cross-path warning.
For its top level performance in all IIHS frontal, side, rear impact and roof-crush tests, and its standard front crash prevention system, the Insurance Institute for Highway Safety grants the S5 the rating of “Top Pick” for 2017, a rating granted to only 205 vehicles tested by the IIHS. The 8 Series has not been tested, yet.