The 12/16 was powered by a four cylinder T-head engine of 2412cc with a Claudel Hobson carburettor. Magneto ignition was used and the engine again had the oil pump in the sump. It had a live axle – there was no chain drive option this time.
In October 1911, the 12/16 received a new four cylinder monobloc L-head engine of 3016cc.
Production of this car ceased in the Sunbeam works with the advent of war, however Rover took up manufacture of the design to provide staff cars for military purposes.
Approximately 4950 were made, plus something like 1781 built by Rover.