Top speed
The highest speed a vehicle is allowed to reach, which it only attains with enough engine power and forgiving ground.
Also known as max speed, forward speed.
Top speed is a cap, not a promise. A vehicle reaches it on hard ground, downhill or with a long enough run, and many heavy vehicles never see their own quoted figure on level soft terrain.
What decides whether a vehicle feels fast is acceleration, and that comes from power-to-weight and terrain resistance rather than from the cap.
Related terms
Power-to-weightEngine horsepower divided by the vehicle's weight in tonnes, the single best predictor of acceleration.Terrain resistanceHow much each ground type slows a vehicle down, quoted for hard, medium and soft terrain, where lower is better.AccelerationHow quickly a vehicle reaches speed from a standstill, which matters far more in practice than its top speed.Engine powerThe engine's output in horsepower, which only means something next to the weight it has to move.