Power-to-weight ratio is the best single predictor of acceleration — it normalizes engine output against how much mass it has to move.
Power-to-Weight = Power ÷ Weight
Where
| Power | Engine output in hp or kW |
| Weight | Vehicle weight in lb or kg |
Worked example
A 300 hp car weighing 3,500 lb has 300 ÷ 3,500 = 0.086 hp/lb, or about 171 hp per ton.
Use real weight. Curb weight plus driver and fuel gives a truer figure than dry weight. Higher ratio means quicker.
Use the Power-to-Weight calculator in the automotive calculators.