The Jaguar Mark IV  is a more recently developed name now commonly used for a range of automobiles built from 1945 to 1949. This range was a return to production, without the brand name S.S., of the SS Jaguar 1½ litre, 2½ litre and 3½ litre models produced by SS Cars (Jaguar didn't exist yet) from 1935 to 1940.  Mark IV is a name now applied in retrospect to separate this model from the succeeding Mark V range.
Before the Second World War the name Jaguar was the model name given to the complete range of cars built by SS Cars Ltd. The saloons were titled SS Jaguar 1½ litre, 2½ litre or 3½ litre. The two-seater sports car was titled the SS Jaguar 100 2½ litre or 3½ litre.
In March 1945 the name SS Cars Ltd was changed to Jaguar Cars Ltd.  All the cars were built on a separate chassis frame with suspension by semi-elliptic leaf springs on rigid axles front and rear.

Specifications
Bodywork
Length: cm (in): 472 (185.8)
Width: cm (in): 167 (65.7)
Height: cm (in): 155 (61)
Wheelbase: cm (in): 305 (120.1)
Weight: kg (lb): 1700 (3920)
Mechanics.
Displacement: inline six 3485 cc (213 cu in), front-mounted
Valve gear: 12
Fuel system: 2 SU carburetors
Gearbox: 4-speed manual
Driven wheels: rear-wheel drive
Maximum power: 125 hp at 4250 rpm
Maximum torque: 250 Nm at 2000 rpm
Maximum speed: 149 km/h (93 mph)