Mercedes 38/250SS

Gianni Marin, The Motor Car, London House and Maxwell 1963

 Mercedes introduced the very fast supercharged SS series of cars  in 1926. Between then and 1931, the Ferdinand Porsche-designed SOHC inline 6 grew from 6.2 litres and 100 hp to 7.2 litres and 160 hp. Power could be increased by about 50% by simply depressing the gas pedal to the floor to engage the supercharger. Cars shown here in competition trim and without body (bottom). Porsche was chief designer at Mercedes from 1923 till 1929.  

Richard Hough, A History of the World's Classic Cars, Harper & Row, 1963