The Jaguar Mark IV (pronounced mark four) is a range of automobiles built by Jaguar Cars from 1945 to 1949. The cars were marketed as the Jaguar 1½ litre, Jaguar 2½ litre and Jaguar 3½ litre with the Mark IV name later applied in retrospect to separate this model from the succeeding Mark V range.
The range was a return to production of the SS Jaguar 1½ litre, 2½ litre and 3½ litre models produced by SS Cars from 1935 to 1940.
Before World War II the model name Jaguar was given to all cars in the range built by SS Cars Ltd with the saloons titled SS Jaguar 1½ litre, 2½ litre or 3½ litre and the two-seater sports cars the SS Jaguar 100 2½ litre or 3½ litre. In March 1945 the company name SS Cars Ltd was changed to Jaguar Cars Ltd.
All the Mark IVs were built on a separate chassis frame with suspension by semi-elliptic leaf springs on rigid axles front and rear.
SS Jaguar and Jaguar 3½ Litre
The 3½ Litre, introduced in 1938, was essentially the same body and chassis as the 2½ Litre but the larger 125 bhp engine gave better performance but at the expense of economy.
The rear axle ratio was 4.25:1 as opposed to the 4.5:1 on the 2½ Litre.