I've noticed some of the power output figures you list are slightly lower than manufacturers' claims. Who is right?
We're simply using slightly different measurements of power output to some manufacturers. We always quote bhp for all cars to allow for accurate, consistent comparisons across different brands.
Some car manufacturers still quote a power output rating called PS, which stands for Pferdestrke (literally, 'horse strength'). It's alternatively known as DIN (Deutsches Institut fr Normung ) hp as opposed to SAE (Society of Automotive Engineers) bhp.
PS is a slightly higher figure than the SAE bhp that we quote, so that's where the discrepancy creeps in.
As a rule of thumb, you can knock off one PS for every 100PS to reach a rough bhp figure. If you want to be completely accurate, multiply the PS figure by 0.9864 to reach the bhp total, or bhp by 1.0139 to get back to PS.
An EU Directive tried to replace the use of PS with kilowatts in the 1990s. One bhp is equivalent to 745.7 Watts, so multiply bhp by 0.7457 to get a kW figure, or kW by 1.341 to do the sum in reverse.
Manufacturers have found that few motorists have any immediate understanding of kW ratings, however, so you're unlikely to see it.