The Jaguar Mk I  1956-1959

The new car broke entirely new ground for Jaguar by being of monococque construction, albeit in hindsight, immensely over-engineered. Although an all new car, it featured a strong family likeness to both of the other ranges, with an XK like front end styling grafted to a center and rear section that  looked remarkably MK VII.like,  although the latters pronounced swept wing line from front to rear was omitted, in favor of a straight line styling. According to some sources it was intended to resurrect a variant of the 2 litre 4 cylinder engine that was to have powered the XK100 if it had ever been marketed, but in the end a new 2.4 litre version of the XK 6 cylinder engine was developed, by shortening the stroke (and the height) of the standard 3.4 litre engine.

The 3.4 variant was most likely produced initially for the US market, where the 2.4 would have been viewed as underpowered. It soon became popular in the home market too, and as the production figues show, sold as well at home as abroad. When the 3.4 was first produced in 1957 the disc brakes were not ready for production, and so early models were fitted with servo assisted drums. Conversion kits were later made available for owners to upgrade their brakes on both 2.4 and 3.4 models, The 3.4 was fitted with the engine from the XK140/150, producing the same 210 bhp when fitted with the B cylinder head and SU carburettors. Cooling had to be increased, so the 3.4 was fitted with a larger grille, similar to the one on the concurrent XK150. This soon became standard on the 2.4 as well to rationalize production. (the original 2.4 grille was similar to the XK140 item). The other main distinguishing external feature was the fitment of cut-away rear wheel spats, so that wire wheels could be fitted and cooling to the marginal drum brakes increased.. Again this was soon fitted to the 2.4 as well

Automatic transmission on the 3.4 (and 2.4 after the 3.4's introduction), overdrive, wire wheels (in body color, chrome or stove enamel), wheel trims for steel wheels (available either as trim rings for use with standard hubcap, or a complete wheeltrim ring which replaced the hubcap), laminated windshield, various radios, Twin exhaust system, and three levels of Tuning Kits for the 2.4  Disc brakes and conversion kits from drum to disc were available. In addition special paint finishes were available to special order.

Wire wheels were 15" and had 60 spokes until the beginning of 1959, when they were changed to stronger 72 spoke wheels.