Power-to-weight in kW per tonne: compare like with like
Normalize power and vehicle mass before comparing a ratio.
Method
Power-to-weight = power in kW ÷ mass in tonnes. Divide kilograms by 1,000 first. Mechanical horsepower and metric horsepower are different units; using the same label for both changes the comparison. Also match the mass definition: kerb mass, laden mass and vehicle-plus-driver mass are not interchangeable.
Worked example
A 150 kW vehicle weighing 1,500 kg has 150 ÷ 1.5 = 100 kW per tonne. Adding 300 kg of occupants and load reduces the ratio to 150 ÷ 1.8 ≈ 83.33 kW per tonne. Power is unchanged; only the denominator has increased.
What to check
A higher ratio is not an acceleration-time prediction. Traction, gearing, torque delivery, aerodynamic drag and test conditions matter. Compare stated power measurements and mass definitions, then use the converter if one source quotes hp or PS.