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Jaguar XJ6

Jaguar XJ6 Published: 10th May 2018 - 0 Comments - Be the first, contribute now!

Fast Facts

  • Best model: Series I 4.2 manual
  • Worst model: Series II 3.4 auto
  • Budget buy: Series II 3.4
  • OK for unleaded?: Use superunleaded
  • Will it fit in the garage? (mm): 4816 x 1772mm
  • Spares situation: Ok except SI front parts
  • DIY ease?: Generally good
  • Club support: Excellent
  • Appreciating asset?: Starting, especially coupés
  • Good buy or good-bye?: Finally being appreciated for being the great car that it is
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Mould-breaking saloon that rewrote the rulebook and still impresses 50 years on. A superior car to Mk2/S-type yet values don’t reflect this – so far. Plenty around but many are shabby rather than top cats so take care when buying

Half a century ago, Jaguar introduced not only the last true world-beating saloon to roll out of Browns Lane but arguably Lyon’s greatest car ever because it’s not simply a replacement for the old Mk2 but landmark design that redefined standards of refinement and comfort that even Rolls couldn’t surpass. Yet for all that, XJ6s remain, as they were when new, astonishing value for money, typically selling for a third of a 3.8 Mk2 can fetch – surely it can’t stay this way for much longer?

Jaguar boss, Sir William Lyons, decreed in 1964, that his new saloon would not only be superior to the Mk2, S-type and the underrated 420 but would be so advanced that it would remain in production for “a minimum of seven years”. He got the first part right but was woefully incorrect on the second – for the XJ6 carried on for almost two decades, in revised S3 guise, and well into the 1990s in XJ12 form!


1968 Launched that September, the XJ6 was a no-compromise car that rewrote the handling and ride rule book while also taking refinement to new levels. The 4.2-litre XK was joined by a new downsized 2.8 (both now topped by Gold Port E-type cylinder heads), the latter mainly designed for certain European tax breaks and said to be a development of the proposed 3-litre for the E-type. The MkX IRS was adapted for an entirely new floorpan.

Power-assisted rack and pinion steering was standard on all bar base 2.8s, which cost a virtual giveaway at £1870 – small wonder that long waiting lists saw used models sell for a 50 per cent surcharge! 1969 “Ninety per cent of motorists want a Jaguar XJ6 – the other 10 per cent want a Daimler,” so said (Lord) Donald Stokes, head of BLMC, latterly British Leyland (read insider Stuart Bladon’s exposé in this issue-ed) so a Daimler Sovereign range duly joins the ranks with slightly higher trim levels to justify, on average, a £60-£80 price hike over the more common Jag.

1972 Long awaited arrival of the 5.3-litre V12, first seen in the E-type the previous year but as an auto only saloon which could be had in optional long-wheelbase form to counter criticisms of mediocre rear seat space. Costing £3726, the Daimler Double Six carried a price premium of £120 over the XJ12. A Rolls-beating Vanden Plas Double Six becomes the flagship at £5362. At the other end of the scale, there are also improved pistons with two valve recesses fitted to the iffy 2.8 to increase its reliability.

1973 Series II hits the showrooms differing little from the original, with chief changes at the front, where a revised bumper height (demanded by US federal legislation), shallower grille and indicator lights located below the bumper. Technically, the SII now boasted better side impact protection, four-pot callipers and vented discs up front, while the auto box was now the swankier, smoother Borg Warner Model 65. There were minor tweaks to the interior with illuminated switchgear and climate control making their début as does the XJC coupé although it did not go on sale until 1975.

1974 By the start of the year, the shortwheelbase chassis was phased with the troublesome, piston popping 2.8, to be replaced with the singleton short wheelbase 3.4 in early ’75, but this isn’t the old much liked Mk2 unit but rather a downsized 4.2 block, good for 167bhp.

1975 V12 models have their final drive ratio altered in 1975 for more refined top-end cruising, while fuel injection also made an appearance on these big-engined versions. XJC hits the showrooms. Just like the XJC, a vinyl adorns V12 saloons too.

1977 A GM three-speed automatic gearbox is employed in the V12 as it could better handle the massive amounts of torque from that 5.3-litre powerhouse. XJC coupé is dropped.

1979 Due to the troubled development of the XJ40 replacement a stopgap SIII is hurried, warmed over by Pininfarina. However, it’s believed to be best XJ6 and XJ12 of the whole litter.

Driving and press comments

The XJ6 was one of the rare cars that gained plaudits even before it was tested. Autocar, after a brief drive, weeks before announcement, said it handled better than the E-type and the ride and handling sets new standards. It also added that because the 2.8 sported some 180bhp, it was so close to the old 340 that it justified not to offer the 3.4… if only Jaguar had! The new Jag certainly impressed those at Car, who proclaimed “the Jaguar XJ6 impresses not just by what it is, but by the value for money it offers in its class – and this is a class which boasts some very worthy competition”. The monthly further added that thanks to supreme driving prowess “It renders superfluous all cars that cost more.”

In its June 1969 road test Autocar said that the XJ6 was the “smoothest and quietest car it had ever driven in” while the handling was “if anything, better than the E-type”. In its conclusion the weekly remarked that if the car were double its £2639 price tag it would still be value, but noted the car even then needed stricter quality control. With more expensive fittings the road test said it would wipe up the quality car market (if only Jaguar had heeded the advice as later on the failings came to haunt the Jag under British Leyland stewardship-ed).

A test of the SII (a Daimler) five years later saw a noted improvement in the heating and switchgear although the testers found – like others – automatic transmission models were too low geared for high speed cruising, with the rev counter’s needle far to close to its red line for comfort, and thought the ride of the lwb chassis not quite as good, which is strange as the longer wheelbase should enhance this.

Nevertheless “A most desirable car in any company” was the verdict.

Rival weekly Motor labelled the 1969 XJ6 4.2 “It comes closer to overall perfection than any other luxury car we have tested, regardless of price. However, a decade on – testing the SII 4.2 which had soared in price from £2365 to £9695 – noted that rivals had caught up fast and the XJ’s “…shortcomings (such as ropey heating and ventilation, muddled switchgear) become more apparent”.

`However, the XJ6 was still a trailblazer that was “wearing its age years well” and ranked its quietness “miraculous” but noted that the gap which was a gulf 10 years previously had shrunken, notably in the heating and ventilation department which (in a later long term test with a base 3.4) wasn’t as good as a Ford Escort Mk2 in their eyes. “Even by today’s standards, it still is a magnificent car, but Leyland had better not sit on their laurels for too long” was the slightly back-handed verdict.

And half a century on? The XJ still greatly impresses in the areas it always has done; ride, refinement, comfort and handling (although this was helped by the special Dunlop tyres that few run on now due to cost). The power steering, ranked good in its day, but still criticised for being too light and lacking feel – has anyone driven a 2.8 XJ6 without PAS? – and not a patch on the weightier set up used by Aston Martin although that’s how the Americans liked it to be.

A good XJ6 remains a dream drive and that sense of occasion is as strong now as it was ever back in 1968. Sadly a lot of them rarely receive the maintenance they deserved over the decades and so, consequently, the surviving majority won’t offer anywhere near the magical combination of a supple ride yet wellmannered cornering of original cars.

The most popular engine is the 245bhp 4.2 and the majority are autos which while good are thirsty due to inherent under-gearing although fuel economy rarely broke into the 20mpg bracket even on the 2.8 (are there many left?) or the superior 3.4, which Motor rated as the smoothest XK unit ever.

It’s certainly more refined than the riotous V12 which provides amazing performance that’s on par with the later supercharged XJRs. Fuel economy is even more dire as you might expect but as most road tests only posted around 15-17mpg for the 4.2 (with the smaller-engined alternatives not much better-ed) does it really matter – on a infrequently driven classic –for the pleasure and thrills this supercar saloon undoubtedly provides?

Road test reports are fine but sometimes it’s takes a layman to cut to the chase – like in a Motor appraisal where a passenger summed the Jag XJ6 up best; “The bloody thing freewheels up hills!”.

Values and the marketplace

Ken Jenkins has been working exclusively on the marque for over 50 years. With a workshop in Nottinghamshire, he maintains classic Jaguars (with a particular focus on engine rebuilds and upgrades), as well as selling new and used parts. A founder member of the Jaguar Enthusiasts’ Club, he’s also the Technical Director for the group. Find out more at

Values have risen over the last couple of years, but you’ve got to be so careful when buying because there are so many misdescribed cars out there, according to Jenkins. The bottom line for any XJ now lies between £9000 and £15.000 but that pennies when compared to a Mk2 or MkX. The key thing is to buy something that’s genuinely good, and not just tarted up.

Genuinely superb examples come onto the market but only very rarely, and when they do you have to dig deep to secure one. The best Series II is worth around £15,000 – maybe slightly more if really kosher. But an equivalent Series I will easily fetch £20,000 – perhaps even £30,000 if it’s flawless. But even these figures are low compared with the XJC coupé, which was offered only in Series II form and for decades couldn’t command anymore than a S1 saloon. However, XJCs now sell for between £30,000-£50,000 if in showroom condition, particularly the V12s.

Daimlers are plusher and more dignified but the stuffy image can put buyers off when condition matters the most. With so few truly superb cars out there, it’s not a good idea to be too choosy about exactly what specification you want, he continues, adding while it’s the 2.8-litre and 3.4-litre models that have long since disappeared. What is in demand is the Vanden Plas, which came automatically in long-wheelbase form so it’s a proper limousine says Ken.

If anything, David Stewart of Peterborough-based Hamiltons Jaguar (01733 551000) feels these prices are somewhat optimistic. He has bought and sold them for three decades and reckons £12-£15,000 irrespective of model – apart from the XJC – point to the fact he sold a VDP a few years ago at auction for less than £13,000 and it recently was resold for roughly the same amount. Stewart is a particular fan of SII that he feels is vastly superior to the original although admits there’s a lot of poor XJs out there.


Forty years ago the XJ12C competed in the prestigious Group 2 racing series and even now you see XJs on the club scene meaning there’s scope for tuning, although you may not want to spoil the car’s character, especially the handling and ride. In fact, simply by thoroughly overhauling the suspension and brakes to ‘as new’ standards – combined with good recommended modern radials – will bring a dramatic change that’s enough for many owners; worn suspension and rear subframe bushes are very common leading to most un Jag-like handling and ride, for example, but harder dampers and springs plus the obligatory ‘poly bushing’ will tighten the chassis which feel soft when compared to moderns. The XJ12 front anti-roll bar is also worth fitting. As the XJ uses superior three or four pot calipers (depending upon car), just better pads may suffice plus DOT 5.1 brake fluid as this reduces the risk of brake fade if used hard.

The XK engine is well known of course and the usual tuning methods naturally apply; bringing the 4.2 up to full fat E-type spec is a good start but there’s a lot more to be done, including taking the unit out to 4.5-litres. or fitting modern fuel injection with mapping but a cheaper route is to fit the S3 head and camshafts with SU HD8 carbs. The main silencers can be removed to increase power.

These cars should run on Shell V Power or similar, as they like 28-30 degrees BTDC at 3000rpm timing with the vacuum pipe disconnected says XJ expert Ken Jenkins. If you want, manual cars can be fitted with the Rover-sourced SD1 ’box although the overdrive can be as good. Autos can be usefully upgraded to the longer-legged fourspeed unit taken from the XJ40/X300.

XJ12 & XJC: Top cats?

Few cars could top the XJ6 when new – except another XJ, such as the XJ12 and the two-door XJC. The former takes all that’s good about the ‘six’; but gives it supercar pace care of that legendary 5.3-litre V12 engine. An auto only yet a wonderful performer that’s almost impossible to wear out, although the XJ6 is the quieter and more serene drive with that legendary burr of the XK engine in full flight. Many magazines continue to bang on about the V12’s understandable miserable economy but for the nominal miles most classics cover is that such a worry; specialist Dave Stewart of Hamilton Jaguar says he regularly sees 16mpg out of his, that’s just a few shy of what many out-of-sorts 4.2s achieve.

The XJC coupé is a bit of an acquired taste. Based on the original (Swb) platform this sportier two-door take offers no performance gains (not that you call the V12 model slow…) and handles the same but the price you pay for those unique looks is considerably more wind noise thanks to those ill fitting doors and frameless glass. Body parts aren’t so prevalent and you can pay double for the privilege of owning one compared to the more practical, roomier saloon. But we’d have one over the XJ-S.

What To Look For


  • Tread carefully if you’re considering a restoration project, because costs quickly escalate; the bodywork is most costly to revive while the trim can also be alarmingly expensive to sort, as can chrome with bumpers around £350 a go.
  • You are likely to spend more restoring an XJ than an equivalent-condition E-type, yet the finished item will be worth far less – which is one reason why most people take the E-type or Mk2 route.
  • Much of the XJ’s appeal lies in its cabin, which is as luxurious an interior as you’ll find. Most XJs feature leather trim, but the 3.4 was introduced for the fleet market so it often came with cloth trim. Any interior that’s seen better days could cost big money to fix – as much as £4000 if all the trim needs TLC. Then there are the carpets and maybe the wood as well to put right. Don’t forget to check the headlining as sagging can be an issue.
  • Series II XJs suffered all sorts of electrical gremlins; early cars are generally better but you still must check everything carefully. Switchgear on earlier models could be horrifically unreliable, the powered window switches usually being first to pack in. Everything is available to put things right, but some bits are costly so be prepared for big bills if there are lots of problems.
  • Some Series II coupés have speedos that read low, as they’re fitted with a 3.31:1 diff but the speedo is calibrated for a 3.54:1. It’s worth checking the speedo against GPS to be sure.
  • Look at as many as you can as it’s what lurks under all the gloss although the interior, it’s easy to remove and used alternatives are around if you don’t mind a spot of patina.
  • The thick carpets soak up and hold water from any window leaks, so feel for dampness The multi-skinned section around the transmission tunnel is another common rot spot that is hard to repair, while SWB sills and floors will have to be adapted from their LWB counterparts.
  • The twin petrol tanks are trouble areas – and no we don’t mean affording to fill them up! Petrol is quite cold and so it produces condensation on the tanks. You then get dampness between the tanks and the body, with obvious results. If you lift the fuel fillers and find rot beneath them, this is the cause.


  • Six-pot XJs are far more common than V12s; of 403,732 XJs built, two-thirds featured the XK straight-six. Offered in 2.8 (Series I and early Series II), 3.4 (Series II and III) and 4.2-litre (all Series) guises, the XK engine needs regular maintenance or its life will be much reduced. Look for a service history, make sure the engine doesn’t sound hollow or rattly and ensure the oil is clean; walk away if it’s like tar. The key is to budget for a rebuild (up to £5000) as soon as the engine is showing signs of wear; delay things and the bills will quickly mount.
  • On a sound XK you should just about hear the tappets; if not they’ve closed up and is a head off re-shim. What you don’t want to hear (apart from crank rumble or piston slap) are timing chains. The top one is doable but the long lower one needs the sump off – happily specialist Ken Jenkins – http://www.ukjag. – has tricks up his sleeve for both scenarios.
  • If a later engine has been fitted, more likely it’s a ‘long stud’ from the S3 but it wasn’t the sturdiest of XK engines, thanks to broken studs, failing head gaskets and even the block’s liners going wonky. The chief cause was internal corrosion, where lack of quality anti-freeze lead to furred up water channels.
  • All six-cylinder XJs feature an XK engine, with a cast-iron block and alloy cylinder head. Because of the latter, anti-freeze levels must be maintained or internal corrosion is guaranteed. Even a wellmaintained engine will need a fresh radiator every 5-10 years depending on use, so you may need to budget for this at £220 plus fitting. Only ever use blue anti-freeze, make sure the viscous fan coupling is tight to turn. Did you know that cheap thermostats can cause hot running, since they are often of an incorrect design?
  • Expect oil pressure of 40psi when cruising, but senders and gauges can be unreliable so plumbing in a temporary gauge is worthwhile.
  • Some oil consumption is normal, but lots of smoke on the over-run or when the throttle is blipped, suggests the valve stem seals have hardened or the valve guides have worn – or it could be that the breather pipe is blocked. Fixing the valve stem seals or worn valve guides will cost at least £1500 for the work, but complications can take this much higher.
  • Look at how much oil is on the car’s underside, as the rear crankshaft oil seal can fail – keeping the oil level between min -max helps, so dip it to check.
  • Once this has happened the engine needs a complete rebuild; a specialist will charge £4000 for the privilege or you could do the work yourself for upwards of £600 – but it’s an involved job. The best thing to do here is to machine the crank seal track and fit a lip seal conversion. If rebuilding a 4.2-litre engine, fit the high-compression pistons from the Series III engine while you’re at it.
  • The 2.8 was infamous for popping pistons but modern fuels (best to use super unleaded in all for the little extra it costs) and specialist serving to the ignition (go electronic as a matter of course) the few remaining should be fine. The 3.4 is better but both are sweet if sedate performers.

Running gear

  • Some Series I automatic transmissions can be clunky with their changes, even when in good condition. However, later cars were better so ensure gear shifts are smooth; even if all seems well it’s worth inspecting the fluid for colour, level and condition. If it’s black and smells foul, a rebuild is on the cards, at £850 upwards. Whatever state everything is in, it’s worth servicing the gearbox when buying – it could transform things.
  • The manual gearbox is strong and most such transmissions were supplied with overdrive. If the overdrive seems slow to engage, it’s probably because the oil needs changing or has fallen below the ideal level; top up/replace with EP 90 oil only.
  • Differentials are tough, but can leak oil. That wouldn’t be so bad, but those in-board rear discs are perilously close to the diff and end up getting covered in lubricant, which is an automatic MoT failure.
  • Putting it right costs at least £1200 because you may as well rebush at the same time; the seals often leak because the brakes have overheated, so you might need to rebuild the brakes as well. Finally, listen out for clonking from worn universal joints, although these are cheap and easy to fix.
  • A lot of XJ universal joints are cheap and don’t last long; expect to pay £45-£50 for a decent joint which should last for years.
  • When checking the rear wheel bearings, there should be a few thou of free play, felt by rocking the wheel side to side. If the car ‘rear-steers’ it’s usually due to the IRS being worn out; rebushing is the cure and while it costs over a grand the transformation in handing on the majority of cars is staggering.
  • Ditto a worn front end ruins the handling; again it’s money well spent as is a full geometry adjustment by a known Jag expert.
  • A hollow knock over bumps suggests that the top wishbone bushes are worn on the front suspension (look also for uneven tyre wear), or that the anti-roll bar links are shot. If you hear more of a twang, check to see whether a front spring is broken. And if the noise sounds more like a crack, then the clamp might well have worked loose on the front subframe mount.
  • The rear brake flexible hoses need replacing every five years. They tend to collapse internally and the brakes will lock on – potentially catching fire.
  • Most XJs featured power steering as standard – police cars and some early 2.8s didn’t. It’s generally reliable but it’s worth checking for leaks; slight weeps are common. It’s worth changing the fluid at service time, using Dexron 2.
  • Finally, tyres as they tell a lot about the car – and owner. Back in their heyday, it wasn’t uncommon to find XJs running on van or municipal tyres to save money. It’s not that bad anymore of course… but certainly cheap tyres sully the drive and points to penny pinching elsewhere.

Body and chassis

  • Because of poor rustproofing, frequently poor build quality and values that have been on the floor for many years, bodged XJs abound so take care when vetting.
  • Few unrestored cars remain in a good condition, while many restorations aren’t very well done due to low values, so be careful if one looks exceptional.
  • Key rot areas include the bottoms of the A-, B- and C-posts along with the sills, rear wheelarches and valances. These areas, along with the spare wheel well and the door bottoms are some of the more obvious places to check.
  • Less obvious are the rear radius arm mounts along with the arms themselves, the metal around the front and rear screens and the bonnet hinge mounting points. The bonnet itself can also corrode, as can the boot lid, wings around the headlights plus the various jacking points; check all these areas very carefully for filler by taking a magnet with you.
  • The radiator support frame and crossmember also dissolves readily, which is an automatic MoT failure; if left to fester, rust then eats into the front chassis structure. Repairs are a big job on the XJ6 and even worse on the XJ12 because of poor access.

Three Of A Kind

Jaguar XJ6 SIII
Quick fix replacement for the original XJ range and many reckon is the best of the lot. Restyled by Pininfarina for a more up to date as well as roomier look, the SIII also boasted a proper fivespeed manual transmission. Other changes included fuel injection for the 4.2 engine and a retuned chassis to accept new generation Pirelli radials. Build quality also improved over the SII and good SIIIs are becoming highly sought after.
Jaguar X300
After the indifferent XJ40 came the revised X300 complete with a traditional Jag-look. If anything, the chassis is even more accomplished while the new straight six engine is both fast and frugal; supercharged XJR is the real scalded cat, never more so on 1997 V8 form (manuals available on earlier straight six). A good X300 is a joy and there’s plenty around so be ultra picky; top XJ40s are starting to gain interest due to their rarity.
Grouping both the Shadow and later associated Spirit/Mulsanne as one, values remain quite low, especially the Spirit/Mulsanne which is why so many are broken for spares although the best examples (Shadows, mainly)are becoming sought after. Mulsanne Turbo has XJ12-like pace if not poise and all Crewe cars have the sense of occasion that even an XJ can’t match. Specialists can keep running costs to fairly containable levels.


Nowhere is the old Browns Lane adage of Grace, Space and Pace more applicable than in a XJ6/12. Get a good one and you’ll find it hard to part with.

Classic Motoring

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