We have a 1935 regulation change to thank for the screaming supercharger bolted to the Mercedes-Benz W25 of the same year.
Rules that dictated a maximum weight of 750kg caused Mercedes to rethink its strategy given that the W25's predecessor was much heavier. With reduced weight came an engine roughly half the size, and to get the power figure back up a supercharger was added. It worked: the W25 produced more power than the larger SSK that came before, and it took the 1935 European Championship in the hands of Rudolf Caracciola.
You can't miss that distinctive high-pitched supercharger whine as it makes its way up the Goodwood hill.