Both the CT4-V and 3 Series Sedan have child safety locks to prevent children from opening the rear doors. The CT4-V has power child safety locks, allowing the driver to activate and deactivate them from the driver's seat and to know when they're engaged. The 3 Series Sedan’s child locks have to be individually engaged at each rear door with a manual switch. The driver can’t know the status of the locks without opening the doors and checking them.
The CT4-V’s standard lane departure warning system alerts a temporarily inattentive driver when the vehicle begins to leave its lane and gently nudges the vehicle back towards its lane. A lane departure warning system costs extra on the 3 Series Sedan.
The CT4-V 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. A system to reveal vehicles in the 3 Series Sedan’s blind spot costs extra.
To help make backing out of a parking space safer, the CT4-V has standard Rear Cross Traffic Alert, helping the driver avoid collisions. BMW charges extra for Cross Traffic Warning on the 3 Series Sedan.
Both the CT4-V and the 3 Series Sedan have standard driver and passenger frontal airbags, front side-impact airbags, driver and front passenger knee airbags, side-impact head airbags, front seatbelt pretensioners, plastic fuel tanks, four-wheel antilock brakes, traction control, electronic stability systems to prevent skidding, crash mitigating brakes, daytime running lights, rearview cameras, available all wheel drive and around view monitors.