sentences:  Only built in Gran Turismo guise with a wheelbase, the 6C 1900 replaced the corresponding 6C 1750 model.Besides the larger displacement, other notable mechanical changes were aluminium cylinder heads, an improved chassis frame and a new transmission.The same upgrades were applied to the 1933 model 6C 1750 Gran Sport which, together with the 6C 1900, form the sixth series of the 6C.