Jaguar has a long tradition of building luxurious saloon cars. From the days of S.S. Cars through today, Jaguar's luxurious yet sporting saloons have sustained the company. In the mid-1950s, Jaguar was riding high with the success of the XK road cars and world-beating C-Type sports racer. The big MkVII and MkIX were surprisingly successful in British Saloon Car racing at the hands of Sir Stirling Moss and others, but these were huge cars and Jaguar wanted to appeal to a broader audience. In a move to boost sales and help their chances on track, Jaguar introduced the mid-size 2.4 and 3.4 saloons. The new mid-sized car debuted in 1955, built on Jaguar's first fully monocoque chassis. The curvaceous body was heavily influenced by the XK sports cars as was the same twin-cam engine which was mated to a choice of manual or automatic transmissions. Further refinements to the shape and mechanical spec brought the MkII of 1959 which featured a larger greenhouse, and a myriad of mechanical improvements including the addition of the hot 3.8 liter engine from the E-Type, which, according to legend was the choice motor for getaway drivers and the police alike. The MkII and its derivatives (such as the fully independent 3.8 S-Type) remained in production until 1969 when the XJ6 was ushered in to consolidate all of Jaguar's saloon models into one line.