The Alfa Romeo 6C name was used on road, race and sports cars made between 1925–1954 by Alfa Romeo. 6C refers to a straight 6 engine. Bodies for these cars were made by coachbuilders such as James Young, Zagato, Touring, Castagna, and Pininfarina. Starting from 1933 there was also a 6C version with a factory Alfa body, built in Portello. In the early 1920s Vittorio Jano got a task to create a lightweight, high performance vehicle to replace the Giuseppe Merosi designed RL and RM models. The car was introduced in April 1925 at the Salone dell’ Automobile di Milano as the 6C 1500. It was based on the P2 racing car, using single overhead cam 1,487 cc inline six-cylinder motor producing 44 horsepower, in the 1928 was presented the 1500 Sport which was the first Alfa Romeo road car with double overhead camshafts.
Source: Wikipedia, 2012