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Jaguar XJ12 Series One, Two & Three

Soon I plan to put up a brand new site, featuring the classic V12 Jaguar saloon, which first broke cover in 1972.

The XJ12, throughout it's long life, was the flagship of the entire Jaguar saloon car range. The majority of cars were powered by the 5.3 litre version of the 12 cylinder engine, and it is these cars, the Series 1,2 and 3, that will be covered.
All the XJ12s covered here were powered by the classic V12 engine that made it's debut in the E-Type Series 3 of 1971, displacing 5.3 litres, and a single camshaft in each bank of cylinders. Series 1s and early Series 2s came equipped with 4 Stromberg carburettors, making way shortly into Series 2 production for fuel injection, which would continue through into Series 3 production. Most Series 3 XJ12s had an improved combustion chamber, and were knowns as the HE (High Efficiency) V12s. A brief history of the XJ12 in its various guises will now follow.

Find XJ12s for sale, including parts and literature.

XJ12 Series 1, 1972-1973

Jaguar knew that by the end of the 1960s, their saloon car range would be getting decidedly long in the tooth, and would be in great need of replacement, so work began on a single replacement, to take over from the Mk2, S-Type, 420 and, ultimately the Mk10/420G also. The end result would perhaps be the best saloon car ever to leave Brown's Lane - the superb XJ6 of 1968. While certain design cues, such as the 420's twin headlamp style, made it onto the new car, the XJ's bodyshell was a completely new design, and one that won universal acclaim both then, and now.

Under the skin things were a little more familiar to seasoned Jaguar followers, albeit refined to suit the new car's dynamics. Independent rear suspension featured, as with all current Jaguars leading up to the XJ's launch, and beneath the bonnet buyers could choose from either a 4.2 or a new 2.8 version of the six cylinder XK engine. It didn't go unnoticed that there was plenty of room either side of the inline-six to accomodate a 'V' engine, which was Jaguar's thinking right from the beginning.

Designs for a V12 engine had been around for some time, with a quad-cam unit already having been tested extensively, bolted into the back of the XJ13 sports-racing car project. Jaguar's engineers used this engine as a basis to produce a version suited to mass production, with the different characteristics required by a road, as opposed to a track, car. For these reasons, and probably cost too, the twin-cam heads were dropped in favour of a simpler, single-cam-per-head, layout, which would end up being used, in various forms, under the bonnet of all road-going XJ12s.

In typical Jaguar style, the V12 engine made it's debut in the sports/GT car of their range, in this case the E-Type, now in Series 3 (convertible or 2+2) form for 1971, to iron out any issues prior to application in the XJ's shell. The XJ12 would hit the showrooms in 1972, in original, short wheelbase form. These cars are now regarded as the most pure expression of the XJ12 design to many enthusiasts. The short wheelbase XJ12 was a good bit lighter than the later XJ12L (L for long wheelbase), and the handling benefited as a result, although in fairness both cars drove and handled superbly. The 'normal' XJ was no slouch in six cylinder 4.2 guise, but with the all-alloy 5.3 V12 engine nestling under the bonnet, the 12's performance lifted the XJ to a new level in terms of performance.

All XJ12s came with a Borg Warner automatic gearbox as standard. The manual shift that was available to E-Type S3 buyers was not offered as an option on the saloon. Most XJ buyers however wanted a swift luxurious motor-car, and Jaguar felt that there would be minimal demand for a manual gearbox version. With more than enough grunt available, the presence of the Borg Warner did little to take the shine off the new Jaguar's epic speed. Top end, the XJ12 would crack 140mph, with 0-60 coming up in a little over 7 seconds.

Visually, the Series One XJ12 looked very similar to it's six cylinder brothers, only the ventilated steel wheels (painted), vertically slatted bonnet grille, and discreet badging, gave the game away. That, and the fact that very little would be overtaking it on the motorway. Internally things were much as normal, with a slightly different aluminium trim around the heater controls, and a tachometer redlined higher than on the '6', differentiating the XJ12 from the XJ6. Peer under the right hand edge of the 12's dashboard and you'd find a lever sticking down - the 12s had a manually-operated choke mechanism, operated by this lever and illuminating to remind the driver that he/she was on enrichment. Fuel economy of the V12 engine was not it's strongpoint, with few saloons eeking out more than 12 or 13 mpg of 5 star fuel, even on a good day. Use the performance of the 5.3 too much and these figures would slide into single-digit mpg with no problem. Unfortunately the XJ12 came to market shortly before the fuel crisis of the early 1970s, blunting sales of this wonderful machine. However cars did sell, albeit in low-ish numbers, especially stateside where large engined saloon cars were still the order of the day. I ran a S1 XJ12L for a few years and it was a superb machine.

One criticism laid at the door of the XJ from the very beginning was it's miserly rear passenger legroom. Jaguar's response, with both the 6 and the 12, was to offer a stretched version, badged as XJ6L and XJ12L. All Series 1 Jaguar V12s were rare sights in the early 1970s, and the lwb versions scarcest of the lot, with little over 700 XJ12Ls being sold.

Just as there had been Daimler versions of the 6, so too would there be a Daimler V12, or 'Double Six' as it was known, re-kindling a model name that first appeared in the 1930s. The Daimler came fitted with revised interior and exterior trimmings, and used an identical engine to the Jaguar variant. Plushest of the lot was the limited production Vanden Plas Daimler Double Six. This model, fitted up at the Vanden Plas works, came with a higher standard of interior trim, wooden dashboard with inlays (also fitted to the door cappings), chrome trims down the side, and usually finished in a metallic paint finish.

XJ12 Series 2, 1973-1979

In 1973 the Series 1 bowed out, to be replaced with the similar-looking Series 2. Externally, the changes were subtle - the front bumper on the S2 was raised and the grille made shallower as a result, and some minor trim alterations took place around the bootlid and rear bumper area. The driver would be sat behind a totally new dashboard, designed with more than a nod to ergonomic considerations, answering another criticism of the Series 1 cars which had a more traditional, and haphazard, layout. The XJ range now started with an all-new 3.4 litre engine, a 4.2, and of course the range-topping 5.3 V12. The early Series 2 XJ12s continued with the quad carburettor arrangement, although this would be usurped by a fuel injection system shortly into production. Again, automatic transmission was the only transmission option for the 5.3 saloon. In addition to the standard 4 door XJ, a new version, based on the short wheelbase bodyshell, was announced - the 2 door XJC (Coupe), available with 6 or 12 cylinders under the bonnet.

By the mid 1970s, Jaguar was well entrenched within the halls of British Leyland, and quality control was suffering. The XJ12 didn't escape, and issues revolving around indifferent vehicle assembly, and the quality of components used, began to hurt Jaguar's reputation, especially in the USA where disgruntled owners were very vocal in their disapproval. Emission control was big news in the 1970s automobile market, and the V12 soon sprouted extra plumbing and gadgetry to help keep the car on sale in the States. The performance of the XJ12, despite the V12's reserves of power, was undoubtably blunted with the introduction of anti-smog kit.

XJ12 Series 3, 1979-1992

By the late 1970s Jaguar had already begun work on an all-new replacement for their existing XJ range. However it's arrival was still a long way in the future, and a freshening-up of the design, which hadn't really altered much since the car's debut in 1968, was due. Instead of employing a home-grown re-design of the XJ, Jaguar turned to Pininfarina, whose designs led to the introduction of the Series 3 in 1979. The car was undoubtably still an XJ, but both 6 and 12 cylinder cars differed considerably from the outgoing cars. Most obvious was the roofline, raised and squared off slightly, to give the car an airier interior and more modern profile. Door handles were now flush-fitting, and the bumpers now had rubber in-fills. The front end was very similar to the Series 2, but the back now featured larger rear light units, incorporating the reversing lamps. Engine options were as before, with the 5.3 heading the line-up, alongside the 12 cylinder XJS. In terms of providing an updated car, while still using the core vehicle's main components, the Pininfarina solution can be seen as a great success, with many owners saying that the Series 3, rather than the 1, was the finest of all 'Series' XJ Jaguars. Introduced in 1979, the Series 3 V12 cars continued to sell strongly until 1992, by which time only the Daimler Double Six version was still in production. The six cylinder S3 had been replaced with the all-new XJ40 design long before, in 1986!

With competition in the luxury car world now coming from Mercedes Benz (560SEL) and BMW, with their technologically advanced V12 750iL, Jaguar had to get a move on with squeezing the 12 pot unit into the XJ40's bodyshell, finally getting the new 6.0 XJ12 onto the market, and consigning the Series 3 to the history books.

XJ12s now have a strong following within the classic car community - with good parts interchangeability between the models, and new and used spares being easily available, the future is looking bright for the classic XJ saloons. There are a number of specialist parts suppliers, in both the UK and overseas, and several clubs provide support to anyone wanting to run, rebuild or even race, a 5.3 XJ12.

Plan is to build up this site to provide a comprehensive view of the Series 1, 2 and 3 XJ Jaguars.
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