The Alfa Romeo 12C or Tipo C was a 12-cylinder Grand Prix car. The 12C-36 made its debut in Tripoli Grand Prix 1936, and the 12C-37 in Coppa Acerbo 1937.
The 12C-36 was a Tipo C fitted with the new V12 instead of the 3.8 straight-eight of the 8C-35.The 12C-36 used the existing six Tipo C chassis.
The introduction of the 4.1 litre 12C-36 at the Tripoli Grand Prix in May 1936 brought Alfa Romeo somewhat in contention again against the German Grand Prix cars.
Although mostly in minor races, the 12C models were driven to several wins in 1936, highlighted by victories in the Donnington Grand Prix and the Vanderbilt Cup in New York. In races with the German cars present a second place at Monza and a third at the Nürburgring, both with the V12 car, were the best results.
The 12C-37 was a new car, with a lower chassis and an engine bored and stroked to 4475 cc, now with roller instead of plain bearings and two smaller superchargers instead of a single large one.
The car suffered poor handling, which could not be cured in time for the 1937 Italian GP, and thus was not successful.
This is given as the reason for Vittorio Jano's resignation from Alfa Romeo at the end of 1937. The 12C-37 was built in four examples, albeit only two were actually assembled for the 1937 Coppa Acerbo and Italian GP.
Early in 1938, the Tipo C (8C-35,12C36) chassis were modified into 308, with the straight-eight engine fitted lower in the chassis and a completely new body. The four 12C-37 chassis were instead assembled into 312 (V12 downsized to 3-litre) and 316 (V16 obtained from two 158 engines fitted to a common crankcase) formula race cars.