For enhanced safety, the front and rear seat shoulder belts of the Ford Mustang 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 M4 doesn’t offer pretensioners for its rear seat belts.
In the past twenty years hundreds of infants and young children have died after being left in vehicles, usually by accident. When turning the vehicle off, drivers of the Mustang are reminded to check the back seat. The M4 doesn’t offer a back seat reminder.
Both the Mustang and M4 have rear cross-traffic warning, but the Mustang has Cross Traffic Braking (automatically applies the brakes) to better prevent a collision when backing near traffic. The M4’s Cross Traffic Warning doesn’t automatically brake.
Both the Mustang and the M4 have standard driver and passenger frontal airbags, front side-impact airbags, driver and front passenger knee airbags, side-impact head airbags, 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, blind spot warning systems, rearview cameras, rear cross-path warning and driver alert monitors.

