Advanced seat belt reminder systems with audiovisual warnings have proven to be highly effective in increasing the belt wearing rates of a vehicle's front seat occupants. While the availability of such advanced SBR systems for the front seats is almost common in some markets and fast-growing in others, also thanks to NCAP incentives, the systems available on the rear seats have so far only offered a basic functionality. In 2014, an upgraded SBR function entered the mass market, and the world's first car with an advanced rear seat SBR system including occupant detection was launched on the Japanese market. This vehicle, the Subaru LEVORG, offers an advanced audiovisual SBR warning for the rear outboard seating positions. This advanced function is enabled by occupant detection sensors designed to detect human rear seat occupants, while being robust against the detection of child restraint systems (CRS) or other objects frequently transported on a vehicle's rear seats. The robustness of the occupant detection and the object non-detection has been tested extensively. Occupants shifted their position forward and laterally away from the nominal seating position. A multitude of CRSs and objects were tested to ensure that they do not trigger unnecessary warnings. Advanced rear seat SBR systems have the potential to significantly increase the belt wearing rates, especially as those tend to be much lower on the rear than on the front seats in almost all countries. As belt load limiters and belt tensioners are more and more available for the rear seats, the advanced SBR systems ensure that more rear seat occupants will benefit from the restraint system enhancements.