The Alvis Speed 20 was a series of cars that was introduced in 1932. The Speed 20 was built in four main variants, the SA, SB, SC, and SD. Although each of these variants had a different wheelbase, the SA and SB shared a 2.5L inline six engine, while the SC and SD were powered by a 2.8L unit. These cars were offered in a range of four seat body styles such as sports saloon, drophead coupe, and sports tourer. Alongside these factory body styles, a rolling chassis was also sold in order to be bodied by a third party coachbuilder. Towards the end of production, Alvis introduced the 3-1/2 Litre SA, which saw the Speed 20 receive a larger, more powerful engine. Production of the Alvis Speed 20 ended in 1936, with the 3-1/2 Litre SA recieving a range of mechanical updates which would see it become a new model, the Alvis Speed 25.