Abstract: The vehicle warning system is adapted to be mounted on the rear window shelf of a vehicle or at the front exterior of a vehicle. It includes a light source such as an incandescent lamp, an L.E.D. display or the like electrically powered by portable dry cells, a vehicle battery or the like, and a flexible, resilient, light reflective sheet, preferably bearing light reflective beads, etc., which sheet is secured by one or more support members directly adjacent to that light source so that vehicle vibrations and/or wind during vehicle travel will flutter the sheet in various directions and flash the light from the light source as a warning to pedestrians, bicyclists and motorists. The support member(s) can be rigid or flexible, resilient and spring-like to aid in the sheet fluttering.