The Kompressor title used by Mercedes is essentially a brand-name version of an already existing function. Supercharging, or turbocharging, has been used to boost a car's power and speed since at least 1921. Of course, the original supercharged car was invented by Mercedes in the first place, so it is only logical that the company would try and make the technology its own.
Supercharged engines, such as the Mercedes Kompressor, use a process known as forced induction to drive more air into the internal combustion engine. Most engines absorb air from the atmosphere, with no mechanical assistance, which necessarily limits their rate of combustion. The mechanical aspect of forced induction in a supercharged engine typically involves the use of a gas compressor or even specialised rotors. The presence of forced induction in a supercharged system allows for more gasoline to be accepted into the chamber at once, greatly increasing horsepower.
Unlike a turbocharger, which is powered by the pressured exhaust leaving the engine, a supercharger is an actively powered mechanical system. The supercharger system is often affixed directly to the engine's crankshaft, whether by a belt or gear. In the case of the Mercedes iteration, the Kompressor, the supercharger is powered by a belt drive.
Differentiating itself from a turbocharger, the Kompressor uses a belt attached directly to the car's crankshaft. This crankshaft is designed to convert the linear motion of the pistons into a rotational energy that is further converted to whatever mechanical or electrical needs the car requires. The number of pistons, or cylinders, a crankshaft has partially determines a car's power, such as the increased power found in V8 (eight-cylinder) engines over V6 (six-cylinder) engines. Thus the supercharger is powered by a belt attached directly to the crankshaft, converting rotational energy into the energy needed to control forced induction.
Inside the Piston
A piston works by providing a confined ignition chamber for a controlled explosion. A spark plug ignites the gas allowed entry into the chamber by the fuel injector, forcing the piston out of the chamber on the explosive wave. The piston pushes upon the crankshaft. Meanwhile, the sudden drop in pressure inside the chamber (due to the quick enlargement of the chamber) "inhales" air from the higher pressure atmosphere. As the piston returns, more gasoline is injected into the chamber, ready to be detonated once again by the spark plug. Rather than forcing the car to "inhale" air from the surrounding atmosphere, which limits air intake to an amount that equalises the pressure, a supercharger acts like an additional fuel injector that squirts air rather than fuel. This means that a higher ratio of air can be achieved inside the piston, since it is not limited by what the atmosphere allows. When ignited by the fuel injector, this more-oxygenated gasoline produces a more powerful explosion.