Quickly switching from war-time production to postwar manufacturing, the Jaguar Motor Company brought the Mk IV to market in late 1945. Given that the last car the company produced was while it was known as the Swallow Sidecar Company (or "SS" for short), the Mk IVs are now recognized as the first "official" Jaguar.

The Jaguar Mk IV did have some updates, including slightly revised axles, brakes, heating, and interior. Overall, however, the model was essentially the same prewar car, with an identical body design for the two saloon and drophead coupe body styles that were on offer. The engine remained the same pushrod six-cylinder engine used in 1940, available in displacements of both 2.5 and 3.5 liters. Cars were referred to by their displacement, with the Mark designation only being retroactively applied.

Jaguar revised the model in 1949 with the introduction of the Mk V, which carried a number of adjustments that made the car more satisfying. All the same, the Mk IV is valued by collectors simply because it is the first true Jaguar. The car also helped the Coventry marque and the British auto industry regain its footing, and set the stage for decades of fine cars.