Horsepower vs Kilowatts: Why the Auto Industry Won't Let the Horses Go
D.Novikov
Kilowatts are more honest and universal, but buyers still respond to horsepower. Why the EV era hasn't killed off Watt's 18th-century marketing trick.
Horsepower has outlived steam engines, carburettors and turbines, and has now quietly moved into the electric era. Formally, power has long been easier to measure in kilowatts, but try telling a customer that a sports car puts out 373 kW. Now say 500 hp — and everything suddenly makes sense.
That’s the paradox. As Autocar points out, James Watt didn’t invent horsepower from scratch — he formalised an easy way to explain to customers how much stronger his steam engine was than a live horse. It wasn’t academic precision; it was selling technology through a familiar image. Two centuries on, carmakers are doing exactly the same thing.
The trouble is that horsepower isn’t as simple as it looks. There’s mechanical horsepower, metric PS or CV, brake horsepower, and power measured at the crankshaft versus the wheels. The differences are small, but in advertising and model names they matter. For instance, 100 metric PS equals roughly 98.6 imperial hp. For the average buyer that’s near enough the same number; for an engineer, they’re different figures.
The kilowatt is more honest. It fits the International System of Units, works equally well for combustion engines, hybrids and electric motors, doesn’t lean on historical romance and doesn’t pretend to be a live horse. But it has a problem: it’s cold. 250 kW reads like a line on a charging-station spec sheet. 340 hp reads like a car you want to take to the test track.
That’s why even EVs are still sold in “horses”. Tesla, Porsche, Hyundai N, BMW M — all of them can quote kilowatts, but the familiar hp figure almost always makes it into the headline. Buyers grasp the hierarchy faster: 150 hp is fine, 300 hp is fast, 600 hp is serious. Kilowatts haven’t earned that emotional scale yet.
The confusion runs deeper in markets where horsepower also drives tax bands, insurance premiums and resale perception. A car with 249 hp sounds reasonable; one with 252 hp triggers a higher tax bracket — even though the difference on the road is almost imperceptible. Manufacturers and importers regularly tune versions to land on the right side of those psychological and fiscal thresholds.
With electric cars this becomes even more obvious. Battery size, weight, range and charging speed often matter more than peak power, yet the “hp” figure still sells better, especially as Chinese brands roll out family crossovers with 500–700 hp, when what the real owner cares about is consumption, battery longevity and winter behaviour.
Horsepower is a poor strict metric unit, but a brilliant automotive language. As long as buyers feel the gap between 200 and 500 hp faster than between 149 and 373 kW, the “horses” aren’t going anywhere.
