During a recent chat over lunch, I heard two non-native speakers discuss the power of car engines, and one of them used the expression
How many PS does the car have?
This is a false friend originating from the German Pferdestärke, The proper English expression would be
How much horsepower does the car have?
or, slightly more colloquial,
How many horses does your car have?
You can still use PS at the end of your letters and emails though ;-).