If you've ever looked up a German or Japanese car spec sheet and seen a figure listed in PS, you've probably wondered whether that's the same as horsepower. Almost, but not quite.
There are four common power units used in the car world: PS, HP, bhp, and kW. Each measures the same physical thing (how much work an engine can do per unit of time), but they're based on slightly different definitions. The differences are small enough to confuse things but large enough to matter when you're comparing specs.
What Is PS?
PS stands for Pferdestärke, which is German for "horsepower." It's the metric version of horsepower, defined as the power needed to raise 75 kilograms by one metre per second against gravity.
One PS equals 0.9863 HP, or about 0.7355 kW. For practical purposes, PS and HP are so close that many people treat them as the same number. A car listed at 200 PS produces 197 HP. You'd never feel that difference.
PS is used across most of Europe and Japan. If you're looking at a BMW, Mercedes, Audi, Volkswagen, Peugeot, Toyota or Subaru spec sheet from a European or Japanese market, the power figure is almost certainly in PS unless it explicitly says otherwise.
What Is HP?
HP is the imperial version, defined by James Watt in the 1700s to describe the output of a steam engine compared to a horse. One HP equals 550 foot-pounds per second, or about 0.746 kW.
In the US, HP is the standard unit for engine output. American car specs list HP. If a Chevrolet Silverado says 400 HP, that's HP, not PS.
The difference between HP and PS is less than 1.5%, so when someone says their car makes 300 PS, telling them it's "really 296 HP" is technically correct but practically meaningless.
What Is bhp?
Brake horsepower (bhp) is measured at the crankshaft using a brake dynamometer. It measures actual engine output before accounting for losses through the drivetrain.
In British and Australian use, bhp and HP are often used interchangeably, and the numbers are nearly identical. A modern car advertised at 200 bhp makes 200 HP.
Where it gets confusing: older American "gross horsepower" ratings from the 1950s and 60s were measured with the engine out of the car, stripped of accessories, and breathing through open exhausts. Those numbers were inflated compared to what the engine actually made in the car. A 1967 Corvette supposedly producing 435 HP was closer to 350 HP in real-world testing. Modern SAE net ratings fixed this, so post-1972 American figures are comparable to European ones.
What Is kW?
Kilowatts are the SI (International System) unit for power and the standard used in Australia for official ADR compliance, fuel consumption testing, and roadworthy documentation.
One kW equals 1.341 HP or 1.36 PS.
When an Australian car ad says "147 kW," that's about 197 HP or 200 PS.
Quick Conversion Reference
| Unit | Multiply by | To Get |
|---|---|---|
| PS | × 0.9863 | HP |
| PS | × 0.7355 | kW |
| HP | × 1.014 | PS |
| HP | × 0.7457 | kW |
| kW | × 1.341 | HP |
| kW | × 1.360 | PS |
For quick mental maths: if you want to convert kW to HP, multiply by 1.34. If you want kW from HP, multiply by 0.75. That gets you within 1% every time.
How Much Power Does My BMW Actually Have?
This is one of the most common questions on forums, particularly for the 7 Series and X3. BMW spec sheets have changed over the years and different markets get different figures. Here are a few examples:
The 1996 BMW 730i (E38) came with the M60B30 3.0-litre V8, making 218 PS (215 HP / 160 kW). Some markets received the 740i with the 4.4-litre M62, producing 286 PS (282 HP / 210 kW).
The 2005 BMW X3 came in several flavours. The 2.5i (E83) made 192 PS (189 HP / 141 kW). The popular 3.0i made 231 PS (228 HP / 170 kW). The diesel 2.0d made 150 PS (148 HP / 110 kW), and the 3.0d made 218 PS (215 HP / 160 kW).
BMW lists both PS and kW in their official documentation. The kW figure is always the primary unit in German documentation.
Advertised vs Actual Power
Published figures are always measured at the flywheel, meaning at the engine itself before any power is lost through the transmission, driveshaft, and differential. By the time that power reaches the drive wheels, you've lost 12 to 20% depending on the drivetrain type.
A front-wheel-drive car loses less (around 12 to 15%) than a 4WD (which can lose 18 to 22% through the additional transfer case and differentials).
A car advertised at 200 HP might put 165 to 175 HP to the ground.
If you want to know your actual wheel power, a rolling road (dyno) run costs between $150 and $300 AUD ($100 to $200 USD) at a performance workshop. They'll strap the drive wheels to rollers and measure power directly. It's the only way to get a real figure, and it's useful if you've done modifications and want to know whether they actually worked.
Why Does This Matter?
Most of the time it doesn't. Knowing your car makes 147 kW instead of 150 PS won't change how you drive it.
Where the numbers matter: comparing two cars from different markets, verifying a modified car's output, checking whether a tune changed anything, or figuring out whether a gearbox or drivetrain component is rated for your engine's output.
If you're shopping for a used European car in Australia, expect the spec sheet to be in PS. Convert to kW for the ADR compliance paperwork and HP if you're comparing with American iron. They're all measuring the same thing. Try TorqueBot Free | Download on iOS | Get it on Android