The 16/20 was the first Angus Shaw-designed Sunbeam. The four cylinder engine had a bore and stroke of 95x120mm, giving a capacity of 3402cc. It was a L-head design, meaning the inlet and exhaust valves were on the same side of the engine. It continued the variable lift inlet valve system of the 12/14. It used magneto ignition. A four speed gearbox was fitted.
As with earlier models it had chain drive with the oil bath chain case.
In June 1906, Shaw and Frederic Eastmead drove one of these cars from John O’Groats to Land’s End covering 1756 miles, without stopping the engine.
By the time of the 16/20, Sunbeam were building 10 cars per week.
For 1908, the bore and stroke of the engine were increased to 105x130mm, becoming a 20hp of 4503cc.
Approximately 600 of this type were built.