A test stand for motor vehicles with a roller assembly having a contact surface for rolling the wheels, with the contact surface being rotatably driven and adapted to be blocked, andor braked, andor released. This floating gate opposes a diffusion layer serving as a control gate via a gate oxide film and is capacitively coupled with the diffusion layer by using the gate oxide film as a dielectric film. A line trench extending between the top surface and the bottom surface of the second dielectric material layer is patterned.