What is power-to-weight ratio?

Power-to-weight ratio measures how much power an engine produces relative to how heavy the car is — and it's generally a better indicator of real-world performance than horsepower figures alone.

How it's calculated:

Power-to-weight ratio is typically expressed as horsepower (or kW) per tonne, calculated by dividing the car's total power output by its weight (usually kerb weight).

Why it matters more than raw power:

A car with a powerful engine but a lot of weight to move can feel noticeably slower than a lighter car with less power but a better power-to-weight ratio. This is why two cars with similar horsepower figures can have very different 0-60 times and overall performance feel — the lighter car often has the advantage, since there's simply less mass for the engine to accelerate.

A useful comparison tool:

Power-to-weight ratio is particularly useful when comparing cars across different classes or price points, since it normalises for size and weight rather than just comparing headline power figures. It's also a big part of why lightweight sports cars can outperform much more powerful but heavier vehicles in real-world acceleration, despite having noticeably less horsepower on paper.