Shortly after Bentley was acquired by Rolls-Royce in 1931, they introduced a new model, the 3.5-liter cars. These cars would go on to become known as Derby Bentleys, based on their production in the Derby, England factory. Against W.O. Bentley's will, these new 3.5 liter cars would shun the sporting reputation of the Bentley name in favor of a more Roll-Royce philosophy of quality and grace. They were originally fitted with a 3.5 liter straight 6 of Rolls-Royce origin but were hopped up a bit with the use of a sportier cam, higher compression ratio, and twin SU carburetors, making the engine good for roughly 110 horsepower. In 1936 the 3 1/2 liter was replaced by a 4 1/4 liter. In total 1234 4 1/4 liter cars were built and while a good majority of them were bodied by Park Ward, numerous coach builders sculpted elegant bodies to be placed on the Bentley chassis. The 4 1/4 liter was replaced in late 1939 by the MkV although some 4 1/4 liter chassis were still being bodied all the way into 1941.