At the maximum possible speed, the engine is running at its point of maximum power, or power peak, and the car is traveling at the speed where air resistance equals that maximum power. A car's speed is limited by the power required to drive it against air resistance, which increases with speed.
The point of maximum power is somewhat lower than the absolute maximum RPM to which the engine is limited, the ' redline' RPM. The power produced by an engine increases with the engine's RPM to a maximum, then falls away.
Laycock de Normanville 'J type' overdrive unit
