Buyer’s guide: Jaguar XJ6/XJ12

By Malcolm McKay

| 30 Nov 2023

Classic & Sports Car – Buyer’s guide: Jaguar XJ6/XJ12

Why you’d want a Jaguar XJ6/XJ12

No other significant vehicle manufacturer was lucky enough to have what Jaguar had.

Boss Sir William Lyonsʼ skill as a stylist, combined with exceptional business acumen – he ran the whole company hands-on, while also styling its cars – was really incredible.

The XJ6 of 1968 was one of his greatest achievements, replacing the Mk2, S-type, 420 and MkX in one brave swoop.

It was so good that Autocar magazine opined Jaguar should double the price of the XJ6 and bill it as the best car in the world, because: ʻDynamically, it has no equal regardless of price .ʼ

Sharing components across the range was one of Lyonsʼ clever tricks; while developing a new dash and crash-safe switchgear for the XJ, he wasted no time in fitting them to E-types, too.

The E-type also came in handy for proving the V12 before it was released in the saloons.

The XJ used tried-and-tested major parts, but was new in many areas.

The body incorporated the latest thinking in vehicle structure, safety and NVH reduction.

The suspension featured anti-dive geometry, polyurethane top mounts, outboard dampers, heavily servoed power steering and all-new Dunlop low-profile tyres developed specifically for the car.

The engine and front suspension were on a subframe, rubber-mounted to the shell.

Rack-and-pinion steering, also on the subframe, was used for the first time on a Jaguar saloon.

The heating, demisting and ventilation were improved, the manual ʼbox was re-engineered to make it quieter, and a ʻtax-breakʼ 2.8-litre version of the XK engine was developed to maximise European sales.

The cooling system received detail attention to improve water flow, and significant effort was put into sound insulation, and door and window sealing.

All contributed to make the XJ6 the most refined sports saloon on the roads. It won Car of the Year in 1969, and when the V12 came it was the ultimate in smoothness, silence and performance.

The limited rear legroom was addressed in 1972/ʼ73 and the XJ continued to be progressively improved through its 24-year life. On refinement, it was never beaten.

Later models offer improved economy (early V12s in particular have a prodigious thirst), though greater complexity means more cost to put things right if they are neglected.

Images: James Mann

Jaguar XJ6/XJ12: what to look for

Trouble spots

Please see above for what to look for before you check out any Jaguar XJ6/XJ12 classic cars for sale.

Engine

The superbly engineered V12 should be whisper-quiet and exceptionally smooth, with the ‘six’ close behind.

They’ll do 150k+ miles between rebuilds if perfectly maintained, but will fail much sooner if neglected.

Beware overheating and headgasket weakness; the complex fuelling and vacuum systems also need watching.

Gearbox

Early Borg-Warner automatic gearboxes were clunky and wore out at 60,000 miles, but the GM400s on later V12s are better.

Check gears/kickdown work and the oil isn’t black.

Rust

When Jaguar XJ6/XJ12 sills rot they affect the security of the rear trailing-arm mounts, which can pull out of the floor if really neglected or poorly repaired with patch welding.

Brakes

Rear brakes on the Jaguar XJ6/XJ12 rust/seize with infrequent use, and are tricky to rebuild without dropping the rear cage.

Check their condition and that the handbrake is effective.

Interior

A perfect interior makes an XJ.

Look out for worn leather, saggy headrests (and headlining), peeling veneers, missing components and tired door trims.

Jaguar XJ6/XJ12: before you buy

Both the six-cylinder and V12 engines are reliable, dependable units if used regularly and maintained well.

Coolant with anti-corrosion inhibitors is vital and must be changed regularly: old anti-freeze can do more harm than good.

Frequent oil changes are highly advisable even on little-used cars. Problems arise from past neglect and long disuse.

Itʼs crucial to check for oil leaks from the back of the engine (in both ʻsixesʼ and V12s): a puddle on the ground every time you stop is rarely appreciated, and if itʼs the rear crank seal (as it often is) then it means taking out the engine and dismantling it to replace the rope seal or fit a lip-seal conversion – an expensive job that often mushrooms into a far bigger bill as other issues are found.

Itʼs rare for the XK units (in particular) to be completely oil-tight, but the extent of the seepage will give an idea of the engineʼs overall state of health – a smoky exhaust is also often a sign of engine wear, too.

Rattles are common with both engines, usually caused by the timing chain at the front; if itʼs bad, urgent replacement is advisable or the tensioner can fail and swiftly cause more severe damage.

Shimming the tappets is tricky and another source of rattles, and camshafts wear rapidly if oil changes are neglected, leading to a loss of power.

Check the age, condition and brand of the tyres: correct Dunlop SP Sport Aquajets for the S1/2 are £1400 a set. Much cheaper tyres are available, but wonʼt suit the car as well.

Jaguar XJ6/XJ12 price guide

Restored/Average/Show

S1 (XJ6-12): £2500-3k/7500-12k/25-30k
S2 (XJ6-12): £1750-2k/6-10k/18-22k
S3 (XJ6-12): £1500-2k/5-11k/15-25k
XJC (6-12): £3-4k/15-18k/35-40k

^{2.8/3.4 c10-20% less than equivalent 4.2; Daimler c10% less than Jaguar}

^{Prices correct at date of original publication}

Jaguar XJ6/XJ12 history

1968 XJ6 launched: 2.8, 2.8 De Luxe, 4.2

1969 Daimler Sovereign 2.8 and 4.2 version

1972 LWB option, XJ12 and Daimler Double-Six introduced

1973 S2: raised bumpers, improved HVAC; 2.8 ends, SWB on 4.2 only (dropped in ’74)

1975 3.4 engine option: 161bhp, cloth trim; Coupé goes on sale (until 1978)

1977 V12 gets GM400 auto

1978 Five-speed Rover manual added

1979 S3: fuel injection on 4.2/V12, bespoke Pirelli Cinturato P5 tyres

1981 V12 gets High Efficiency cylinder-head design: better economy and performance

1987 Six-cylinder S3s replaced by XJ40

1992 Last V12 S3s built

The owner’s view

“As a teenager, it was the ultimate,” recalls Steve Gray. “If you saw someone driving one of these, you knew they’d made it. I just love that wavy front: it was one of the last of the real Jaguars.

“I searched high and low for a good V12. I bought this one in 2014, with a full service history.

“It had been through seven owners, but most of them had stored it, fortunately well – it’s only done 70,000 miles and is totally original apart from a respray.

“It was absolutely solid, but I had it stripped back to bare metal at the Haynes Museum workshops. Any small rust spots they found were cut out, with new metal welded in, and it was completely repainted two years ago.

“The factory build sheet showed that it was fitted with spotlights originally, so I sourced a new set and put them on.

“Mechanically, it’s been very reliable: I get 15mpg on short runs, but up to 18mpg on longer journeys.”

Also consider

The Cadillac Seville (left) and Mercedes-Benz 116-series are alternative buys

CADILLAC SEVILLE

Cadillac’s compact saloon with an injected 5.7 V8 matched a 2.8 XJ’s pace and size. For 1980 it went front-drive with a 6.0 V8 or 4.1 V6, then from 1986 4.1-4.9 V8s. Rarely seen outside the US.

Sold 1975-’91 • No. built 558,831 • Price now £5-25,000*

MERCEDES-BENZ 116-SERIES

European Car of the Year 1974 and as quick as an XJ, Mercedes’ S-Class had a 2.8 ‘six’ or 3.5/4.5/6.9V8s, Bosch ABS and electronic injection, with optional hydropneumatic suspension.

Sold 1972-’80 • No. built 473,035 • Price now £4-55,000*

^{*Prices correct at date of original publication}

**Jaguar XJ6/XJ12: the Classic & Sports Car verdict**

Backed by superb parts supply and club support, Jaguar and Daimler XJs can be among the most affordable luxury sports saloons to own: prices are rising, but they remain fair value.

They can still rack up hefty bills if major body or engine work is needed, though, so try to buy a good car and look after it properly.

Pay particular attention to the bodywork and to maintenance history – and make sure it’ll fit in your garage!

FOR

With most parts available and surprisingly inexpensive, an XJ needn’t be costly to own
Their style always commands respect
They are supremely comfortable to ride in

AGAINST

Almost all have endured a period of neglect, which can come back to bite the unwary
Fuel costs are high
Parts quality is variable

Jaguar XJ6/XJ12 specifications

Sold/number built 1968-’92/98,227 S1s, 91,227 S2s, 10,487 coupés, 132,952 S3s
Construction steel monocoque
Engine iron-block, alloy-head, dohc 2792/3442/4235cc ‘six’, twin SU HD8/HS8s or Lucas-Bosch injection; all-alloy, ohc 5343cc V12, four Stromberg carbs or injection
Max power 140bhp @ 5150rpm-299bhp @ 5500rpm
Max torque 150lb ft @ 4250rpm-318lb ft @ 3000rpm
Transmission four/five-speed manual (optional overdrive on four-speed) or three-speed auto, RWD (LSD on V12)
Suspension: front wishbones, coil springs, telescopics, anti-roll bar rear twin spring/dampers, parallel links, halfshafts as upper links, trailing arms
Steering power-assisted rack and pinion
Brakes discs (vented front S2/V12s), servo
Length 15ft 9½in-16ft 3¼in (4813-4959mm)
Width 5ft 9½-9¾in (1765-1770mm)
Height 4ft 5½-6in (1359-1372mm)
Wheelbase 9ft ¾-4¾in (2762-2865mm)
Weight 3389-4234lb (1537-1920kg)
Mpg 12-24
0-60mph 11.2-7.4 secs
Top speed 117-136mph
Price new £14,495-25,995 (1984)