For enhanced safety, the front and rear seat shoulder belts of the Lexus RC have pretensioners to tighten the seatbelts and eliminate dangerous slack in the event of a collision. The Honda Civic Si doesn’t offer pretensioners for the rear seat belts.
The RC’s optional pre-crash front seatbelts will tighten automatically in the event the vehicle detects an impending crash, improving protection against injury significantly. The Civic Si doesn’t offer pre-crash pretensioners.
The Lexus RC has standard driver and front passenger side knee airbags mounted low on the dashboard. These airbags helps prevent the driver and front passenger from sliding under their seatbelts or the main frontal airbags; this keeps them better positioned during a collision for maximum protection. Knee airbags also help keep the legs from striking the dashboard, preventing knee and leg injuries in the case of a serious frontal collision. The Civic Si doesn’t offer knee airbags.
The RC offers all-wheel drive to maximize traction under poor conditions, especially in ice and snow. The Civic Si doesn’t offer all-wheel drive.
To help make backing out of a parking space safer, the RC’s standard rear cross-path warning system uses sensors in the rear bumper to alert the driver to vehicles approaching from the side, helping the driver avoid collisions. The Civic Si doesn’t offer a cross-path warning system.
The RC’s driver alert monitor detects an inattentive driver then sounds a warning and suggests a break. According to the NHTSA, drivers who fall asleep cause about 100,000 crashes and 1500 deaths a year. The Civic Si doesn’t offer a driver alert monitor.
Both the RC and the Civic Si have standard driver and passenger frontal airbags, front side-impact airbags, side-impact head airbags, four-wheel antilock brakes, traction control, electronic stability systems to prevent skidding, crash mitigating brakes, daytime running lights, lane departure warning systems, rearview cameras and available rear parking sensors.
The Lexus RC weighs 831 to 1002 pounds more than the Honda Civic Si. The NHTSA advises that heavier cars are much safer in collisions than their significantly lighter counterparts. Crosswinds also affect lighter cars more.

