It is hard to know what inspired Jaguar engineering chief Claude Baily to start work on a 12-cylinder engine, but the sound of Ferraris howling through the darkness at Le Mans maybe played a role.
Development of a V12-powered Jaguar reportedly began shortly after the C-Type’s 1951 Le Mans 24 Hour victory and with the brand’s greatest achievements still to be recorded by D-Types with straight-six power units.
By 1960, Baily and his engineering team at Jaguar were proposing V12s that ranged in size from from 4.9 to 7.6 litres, with single or twin-cam cylinder heads and the option of fuel injection. Four years later, several prototype engines had been built, with some powering the biggest, heaviest Jaguar, the Mark X Saloon, as they underwent testing.
A dry-sumped, all-alloy, injected 5.0-litre unit was developed for competition use, while cast iron blocks were produced for noise testing against the lighter alloy blocks.
Jaguar’s intentions to race a V12 didn’t surface until 1967 when the company conducted clandestine tests of a car that might have become a Le Mans 24 Hour front-runner against the established Fords and Ferraris.
Jaguar’s XJ13 was a broad and sensual sports prototype with a wrap-around windshield and no roof. There were vestiges of D-Type in its shape, but the front and rear mudguards bulged to accommodate huge magnesium alloy wheels and racing tyres. The cockpit had seating for two but was intended for driver-only operation at speeds up to 300km/h.
Tests with an engine producing 373kW confirmed the car’s potential, but a Le Mans rule change banning prototype cars with engines larger than three litres brought the project to a halt.
The XJ13 was wheeled away and almost forgotten until January 1971, when it joined the unreleased E-Type V12 for production of a promotional film. While running at speed on the banked MIRA Proving Ground circuit in England, a tyre failed and pitched the XJ13 on to the grassy infield.
Although the car rolled several times and was seriously damaged, diminutive test driver Norman Dewis crouched low in the cabin, ‘gripping the steering wheel for dear life’ as he would later recall, and survived.
The wreck of the racing car was returned to storage but the E-Type with its 5.3-litre derivative V12 soldiered on, astonishing the world and especially the North American market with its new power unit.
V12 E-Types retained the overall style of the six-cylinder original but were significantly wider and heavier. All of the Fixed Head Coupes had 2+2 seating and many used three-speed automatic transmissions.
The Roadster was more commonly seen as a four-speed manual and weighed 1515kg against 1206kg for the 4.2-litre Series 1 roadster. From an age before cars sold in the USA needed to disclose actual engine outputs, the 4.2 had been rated at 197kW. In 1971, the more sophisticated V12 would be credited realistically with 186.5kW.
Jaguar from the beginning had seen its V12 powering large sedans and 1972 brought that intention to fruition. The XJ body had been designed from the beginning to accommodate an engine larger than Jaguar’s 4.2-litre and the V12, even with quadruple carburettors rather than fuel injection, was an easy fit.
V12 sedans were produced in Jaguar and Daimler variants, with Daimler V12s less common. Series 1 versions of the Daimler Vanden Plas Double Six rank amongst the company’s more exclusive models with just 354 built.
Also uncommon were two-door versions of the Double Six with a total of 407 made from 1975-78. Next in line for V12 power was the XJS Coupe.
It arrived in 1975 and was notionally intended to replace the ageing E-Type.
However, the XJS was a very different style of car and able to attract a broader market than could be captured by the Series III E.
Sadly for Jaguar and its exceptional engine, world politics would move much faster than the process of automotive development. Well before the XJS was launched on to the crucial North American market, global oil shortages had sent fuel prices soaring and blighted demand for big-engined cars.
The XJS was still very successful in the USA and remained available until 1996, during which time almost 80,000 V12-engined cars had been sold worldwide.
Despite concerns about fuel economy, Jaguar remained keen to continue with V12 versions of its XJ sedan. From 1974-79, more than 16,000 of the XJ12 Series 2 were sold, after which Jaguar kept its Series 3 XJ12s and Daimlers in production until 1992, well after the mainstream XJ6 S3 had been replaced by the XJ40.
The shape would eventually change in 1993, with the XJ40-bodied XJ12 adopting a version of the 6.0-litre engine that had been available since 1989 in the XJR-S.
The last model to use Jaguar’s V12 engine was an X300-bodied Daimler Double Six that remained in production until April 1997.
DAVID EVANS – JAGUAR XJS 6.0 COUPE
David Evans’ XJS was a rarity from birth, and whilst in his care has been transformed in ways that take it very close to the definition of ‘unique.’
The big coupe began life in 1993 as a 6.0-litre XJS with three-speed automatic transmission. It had been earmarked as a display car for the Sydney Motor Show, and once that duty was done headed to a new home in Melbourne.
Some years later the car was in the hands of Jaguar tuning specialist and racer, Mike Roddy, and from there moved into David Evans’ ownership. David had previously owned a V12 and appreciated the untapped potential of the engine, so therefore wasn’t perturbed when Mike suggested modifications which would turn the car in to a facsimile of Jaguar’s very potent XJR-S.
Mechanical improvements included a minor rebore plus new pistons, camshafts and valves plus a high-efficiency fuel rail and intake tract that pulled cool air from alongside the headlights. All of this was controlled via an Autronic management system which enabled the engine to deliver a reliable 400bhp, or around 297kW.
“It could produce more if I wanted it,” David said. “However, I needed something that would be tractable enough to drive and be a daily-use car.”
Other significant changes included replacement of the original GM400 transmission with a five-speed Getrag manual and lightweight competition clutch which, according to David, has “transformed the car”. With the same 2.88:1 final drive ratio as the factory XJR-S manuals, top speed would be in the vicinity of 255km/h.
“The wheels are special too,” David commented. They are off an Aston-Martin DB7, but with billet centres which Mike Roddy’s son had specially made for the car.”
David has a few vehicles and needs space so the XJS is currently for sale at $75,000 — far less we suspect than the amount invested to reach this stage of development.
It you’re interested, call David Evans on 0418 322 273
TOM GARLICK – JAGUAR XJ12 S3 SOVEREIGN
The closure of Manton Motors after 30 years as a prominent Mini and Jaguar agency was bad news for many but not XJ-loving Tom Garlick.
Tom was at the time in the market for a Jaguar XJ6, but when offered an executive driven XJ12 from Manton’s liquidated stock he didn’t think twice.
“The car was Solent Blue, less than a year old and showing around 17,000km,” Tom said.
“It had been allocated to one of the dealership execs who lived some way out of Melbourne so the kays rolled over pretty quickly.
“A mate who was a wholesaler got it at a good price and it became my business car for the next ten years. I got the balance of the warranty but nothing major went wrong and maintenance was a business expense.”
When Tom sold the business around 25 years ago he bought the Jaguar for private use and continued to run it quite regularly as a family and club car.
To date, Tom’s XJ12 has clocked up 407,000 kilometres without any major work on the engine or its GM400 automatic transmission.
“Most of the distance was done at highway speeds,” he said. “I used to run Melbourne-Adelaide a lot and to Sydney, and it was the perfect car for that type of trip – very comfortable and never stressed.”
Regular maintenance, with particular attention to the cooling system has been crucial to the engine’s survival, including changing to an electric fan in place of the original. Tom credits a dedicated mechanic at Mike Roddy’s workshop for keeping the car in top condition.
“The Interior is holding up very well, but after the car retired from business use the body was resprayed by a painter named Peter Todd who made it look better than factory,” Tom commented.
“As to the future I’ve got a nephew with a S3 XJ6 who might be the next custodian, but my wife likes to go out in the car and we will continue as long as that is possible.”
PHIL SMITH JAGUAR E-TYPE V12 FHC
Phil Smith’s history of E-Type ownership dates back to the 1980s, but his first contact with a Jaguar occurred even earlier. It therefore came as no surprise once life rolled by that he would find space for the biggest E of them all.
“My dad bought a 240 sedan in the 1970s from his boss who was the original owner,” Phil recalled. “It was a manual and a lovely car. I learned to drive in it and still had it until quite recently.”
At 23, Phil acquired a Leaping Cat of his own; a Series 1.5 E-Type coupe that cost him $13,000 and which he sold for $30,000 after prices had soared.
“That car became a house deposit, but about 15 years ago I got hold of this E-Type,” Phil said. “It had been through a few owners and a couple of colour changes — the Heritage Certificate shows it as British Racing Green originally — and needed some work, but it was a V12.”
Almost straight away, Phil commissioned Jaguar specialist Mike Roddy to replace the automatic transmission with a manual and sort some problems with the massive bonnet which didn’t close as it should and was showing some rust.
Another Roddy touch was the neat number-plate mounting, ensuring no more discussions about absent front plates on E-Types.
“My early car didn’t have a plate at all and several times I was stopped by the police. Never got a ticket, I think they just wanted a look at the car.”
In common with other owners of V12s in this group, Phil avoids a massive annual rego slug by keeping his car on Concessional Registration and attending club runs when time allows.
“I take it out when I can and my son loves the car, so maybe in the future it will be handed on to him, time will tell.”