Question 1

Why is road tax based on horsepower rather than kW?

Accepted Answer

In Russia the vehicle tax is set in roubles per horsepower — a historical convention. The registration papers list both kW and hp, and the tax uses the hp figure. To convert, multiply kW by 1.35962: e.g. 100 kW × 1.35962 ≈ 136 hp.

Question 2

How does metric horsepower differ from mechanical?

Accepted Answer

Metric hp (PS/CV/ch) = 75 kgf·m/s = 735.499 W; mechanical hp = 550 ft·lb/s = 745.700 W — about 1.4% more. German, French, and Russian cars quote metric hp; American cars use mechanical hp. So 200 PS ≈ 197 hp, not the same number.

Question 3

How does engine power affect acceleration?

Accepted Answer

0–100 time depends not only on power but on torque, vehicle mass, and the gearbox. Roughly, twice the power gives twice the acceleration, all else equal — but a 150 hp turbodiesel can out-pull a 200 hp naturally aspirated engine thanks to torque.

Question 4

What is the engine's real power?

Accepted Answer

Quoted figures (DIN or SAE) are measured on a bench without accessories. Actual "at the wheels" power on a dyno is 15–25% lower because of drivetrain losses. Chip tuning usually adds a real 10–15%, not the 30–40% marketers promise.

Question 5

What are peak and continuous power on an electric motor?

Accepted Answer

Electric motors have a short-term peak rating and a continuous (nominal) one. A Tesla Model 3 AWD peaks around 393 hp but sustains closer to 200 hp — important on long climbs or when overheating. The Porsche Taycan uses active cooling to hold peak power longer.

kW ↔ HP Converter — Free Online Calculator