TWIN TEST
We reunite the very last saloon cars to use Jaguar’s best-loved engines, in their anniversary year.
WHILE IT has used other engines from other manufacturers, and adapted engines to its own specification, Jaguar has produced only four engine designs completely from scratch in over 100 years of history and over 75 years of the Jaguar name plate. And to us, it seems fitting to observe that the first and second of those engines last saw service in models which, in 2024, are celebrating anniversaries. Jaguar’s first engine, the XK, was introduced in 1948 and – while the limited run Daimler DS420 ensured it lasted util 1992 – its last home as a mainstream production engine was in the Series III XJ6 launched in 1979. Jaguar’s second engine was originally designed for the XJ – a V12 unit initially displacing 5.3 litres, fitted to the Series 3 E-type, the XJ-S, and the XJ12 before being replaced by a supercharged V8 for 1997. The last car to bear the XJ12 name – and the final Jaguar V12 – was the X305 XJ12, launched in 1994 as part of the X300 saloon series.
As one of these swansong models turns 30 and the other turns 45, we thought it would be interesting to bring them together to see how the XJ evolved, to pay homage to two great saloon car families, and to mark the passing of two of Britain’s most iconic engines.
Jaguar XJ6 Series III
The XK engine may have been designed for Jaguar’s saloon car range, but it made its debut in the XK120 sports car of 1948. Plans for a 2.0 four cylinder variant called the XK100 were ultimately ditched – while Jaguar had offered four cylinder saloons with engines derived from Standard designs, its post war offerings from the MkV onwards were too large to warrant the use of the engine and smaller anticipated production numbers stopped it from being cost effective to put it in the sports car. From the 1950s through to the 1980s it powered pretty much everything Jaguar built, including some Daimler badged models – only the XJ-S and the Daimler V8-250 escaped its influence. Built in a multitude of sizes from 2.4 litres to 4.2 litres, it was the powerplant behind what many regard as Jaguar’s golden era, and was only superceded by the AJ6 in the XJ40 after almost forty years of production for mainstream models. Even then, it wasn’t over – the Daimler DS420 limousine would survive into the 1990s using the same powerplant.
The Series III was the last in the line model for the original XJ6 – and while we accept that the Daimler DS420 kept the XK engine alive for a further six years, the fact is that it was a handbuilt commercial special rather than a mainstream production model. We therefore think that it’s fitting to acknowledge the Series III as the final home for an engine available to the mass market, Jaguar’s first indep
