If the height of the racetrack is increased, then the speed of the car will decrease, because motion can be described in terms of potential and kinetic energy. As the height of the track increases, the potential energy of the car also increases. However, as the car moves down the track, the potential energy is converted to kinetic energy, which is the energy of motion. If the height of the track is increased, the car will have more potential energy at the start, but this potential energy will be converted to kinetic energy more slowly, resulting in a lower speed.