Detecting how a vehicle is steered and then alarming drivers in real time is of utmost importance to the vehicle and the driver’s safety, since fatal accidents are often caused by dangerous steering. Existing solutions for detecting dangerous maneuvers are implemented either in only high-end vehicles or on smartphones as mobile applications. However, most of them rely on the use of cameras, the performance of which is seriously constrained by their high visibility requirement. Moreover, such an over/sole-reliance on the use of cameras can be a distraction to the driver. To alleviate these problems, we develop a vehicle steering detection middleware called V-Sense which can run on commodity smartphones without additional sensors or infrastructure support. Instead of using cameras, the core of V-Sense senses a vehicle’s steering by only utilizing nonvision sensors on the smartphone. We design and evaluate algorithms for detecting and di↵erentiating various vehicle maneuvers, inclu...