Abstract: A vehicular deceleration warning system for providing a warning that impending deceleration and braking may occur. The vehicular deceleration warning system includes an accelerator pedal pressure sensor for detecting removal of a driver's foot pressure from the accelerator pedal. The sensor comprises a housing. The housing includes a bottom wall with a substantially planar bottom for securely removably mounting on a front surface of the pedal. The housing also includes a top wall with a substantially planar top surface for pressing a foot against. A first plate is mounted in the housing adjacent to the top wall of the housing. A second plate is mounted in the housing adjacent to the bottom wall of the housing. A biasing means is provided for biasing the second plate away from the first plate. A signaling means is provided for visually warning the following vehicle of the impending deceleration of the first vehicle. The signaling means is designed to illuminate when activated.