Recently came across this unit and I found out by googly. Thought of sharing the same. Here it goes

PS is the BHP(Brake Horse power) of the vehicle

eg: 100PS@5500rpm means the vehicle delivers 100bhp of max power when the engine runs at 5500rpm(revolutions per minute)

PS and BHP are unit of power

This unit (German: Pferdestärke = horse strength) is no longer a statutory unit, but is still commonly used in Europe, South America and Japan, especially by the automotive and motorcycle industry. It was adopted throughout continental Europe with designations equivalent to the English horsepower, but mathematically different from the British unit. It is defined by the Physikalisch-Technische Bundesanstalt (PTB)[7] in Braunschweig as exactly:

1 PS = 75 kilopond-meters per second
(75 kp·m/s)×(9.80665 N/kp) = 735.49875 N·m/s ≈ 735.5 N·m/s ≈ 735.5 W ≈ 0.7355 kW ≈ 0.98632 hp (SAE)

The PS was adopted by the Deutsches Institut für Normung (DIN) and then by the automotive industry throughout most of Europe, under varying names. In 1992, the PS was rendered obsolete by EEC directives, when it was replaced by the kilowatt as the official power measuring unit. It is still in use for commercial and advertising purposes, as many customers are not familiar with the use of kilowatts for engines