Introduced in 1966, the 420 marked the culmination of Jaguar’s highly successful medium-sized saloon lineage, which originated with the Mark 1 in 1955. Essentially, it was a revamped version of the S-Type, featuring a front end reminiscent of the larger Mark X, replacing the Mark 2-style front of its predecessor.
Evolved from the well-received Mark 2, the S-Type/420 set itself apart mechanically with an independent rear suspension—a feature first introduced in saloon form with the Mark X. The 420 boasted a standard 4.2-liter XK six-cylinder engine in twin-carburetor 245bhp configuration. Notable enhancements included alternator electrics, a limited-slip differential, and dual-circuit brakes. The option for variomatic power-assisted steering was available. Opting for Borg Warner automatic transmission slightly reduced the top speed, yet acceleration remained unaffected.
In comparisons among automatic Jaguar saloons, Motor observed that “the 420 has a useful edge over the 3.8 S-Type in the middle speed ranges and is just about level pegging with the more powerful (but much heavier) Mark X.” Despite its superior handling and extended range compared to the Mark 2, the S-Type and 420 have often dwelled in the shadow of their esteemed predecessor, and their value tends to be underestimated even in contemporary assessments.
Source: Bonhams Cars
