Power-to-weight
Engine horsepower divided by the vehicle's weight in tonnes, the single best predictor of acceleration.
Also known as hp/t, power to weight ratio, p/w.
Power-to-weight is what makes a vehicle responsive. Above roughly 20 horsepower per tonne a vehicle accelerates briskly, below 10 it labours out of every corner and up every slope.
power-to-weight = engine horsepower / weight in tonnesIt is not the whole story: terrain resistance divides into it, so two vehicles with identical ratios move very differently if one is built to cross soft ground.
Related terms
Engine powerThe engine's output in horsepower, which only means something next to the weight it has to move.WeightThe vehicle's mass in tonnes, which sets its power-to-weight ratio and decides who wins a collision.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.