Nowadays, vehicles are involved deeply in human life, especially for passengers and goods transportation, and along with technological advancements, the autonomous car becomes one of the most concerning issues. With the aim of management and control, many kinds of sensors are situated in different parts of the vehicle to ensure safe and reliable driving, but they also drain out more power from the electric circuit. In this work, a rotational switched-mode water-based triboelectric nanogenerator (RSW-TENG) as battery-free device is demonstrated, in which its capability of converting rotational kinetic energy into electricity and detecting the road slope as well as the wheel speed is carefully investigated. The spatial relation between water and electrodes during operation has a great effect on the electrical outputs of RSW-TENG where they represent a negative proportional relationship with the slope angle ranging from 0 degrees to 80 degrees; meanwhile, a positive proportional relationship with rotational speed is observed instead. The practical evaluation with a prototype of vehicle wheel attached RSW-TENG is implemented, and it exhibits a reliable and accurate performance under different inclinations and driving speeds. These results point out that the RSW-TENG could be an appropriate selection for monitoring and enhancing driving safety. (C) 2022 Elsevier Ltd. All rights reserved.