The XJ line received a facelift in Autumn 1973 for the 1974 model year, thereafter known as the Series II; retrospectively the earlier cars were referred to as the Series I. The 4.2 L XJ6 straight-6 engine (most popular in the United Kingdom) and the 5.3 L V12 XJ12 were continued with an addition of a 3.4 L (3,442 cc; 210.0 cu in) version of the XK engine available from 1975. The Series II and Series II coupé were the last Jaguar models with direct input by Sir William Lyons before his retirement.[12]

Initially, the Series II was offered with two wheelbases, but at the 1974 London Motor Show Jaguar announced the withdrawal of the standard wheelbase version: subsequent saloons all featured the extra 4 inches (10 cm) of passenger cabin length hitherto featured only on the long-wheelbase model.[13] By this time, the first customer deliveries of the two-door coupe, which retained the shorter standard-wheelbase (and which had already been formally launched more than a year earlier) were only months away.