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 CT5-V are reminded to check the back seat if they opened the rear door before starting out. The S4 doesn’t offer a back seat reminder.
Over 200 people are killed each year when backed over by motor vehicles. The CT5-V (except Blackwing Manual) has standard Reverse Automatic Braking that uses rear sensors to monitor and automatically apply the brakes to prevent a rear collision. The S4 doesn’t offer backup collision prevention brakes.
The CT5-V has a standard blind spot warning system which uses sensors to alert the driver to objects in the vehicle’s blind spots where the side view mirrors don’t reveal them. A system to reveal vehicles in the S4’s blind spot costs extra.
To help make backing out of a parking space safer, the CT5-V has a standard rear cross-path warning system, which uses sensors in the rear bumper to alert the driver to vehicles approaching from the side, helping the driver avoid collisions. Rear cross-path warning costs extra on the S4.
Both the CT5-V and the S4 have standard driver and passenger frontal airbags, front side-impact airbags, driver and front passenger knee airbags, side-impact head airbags, front seatbelt pretensioners, height adjustable front shoulder belts, plastic fuel tanks, four-wheel antilock brakes, traction control, electronic stability systems to prevent skidding, crash mitigating brakes, daytime running lights, lane departure warning systems, rearview cameras, available all wheel drive and around view monitors.