Jaguar XJ6 2.8 vs Rover 3.5 Litre Coupé: changing of the guard

By Simon Hucknall

| 4 Jun 2025

Classic & Sports Car – Jaguar XJ6 2.8 vs Rover 3.5 Litre Coupé: changing of the guard

As he belted down the M4, wrangling a Rover P5B in the 1970 flick The Man Who Haunted Himself, you could imagine Harold Pelham’s nemesis behind the wheel of a new Jaguar XJ6, instead of the Lamborghini Islero used in the film.

Low, rakish and wholly en vogue, it would have been well suited to Pelham’s caddish alter ego and the antithesis of his everyday Rover, which remained the embodiment of upper-middle-class urbanity.

You could see why. The Rover’s and Jaguar’s designs were only separated by a decade, but that period wrought seismic change across the British motor industry, as austere 1950s conservatism was banished in favour of the sleek Modernism of the ’60s.

The Rover P5B’s Buick-derived V8 gave the ageing model its second wind

Nonetheless, by 1967, after its P5 had been through three iterations as the six-cylinder 3 Litre, Rover elected to give the model a final lease of life as the 3.5 Litre (or 3½ Litre), making it the first British production car powered by the now ubiquitous Buick-derived 3528cc V8.

Given that the ageing Rover was set to be the only true British rival for Jaguar’s upcoming XJ6, its new engine was timely – and transformative.

Was it transformative enough, though, to convince a new breed of middle managers that the only way was Solihull, not Browns Lane?

The Rover P5B has impressive cross-country pace

There’s no better way to find out than with fine examples of each, both manufactured in 1972.

The Rover, which went almost unchanged in its six-year life, is the more expensive Coupé model, costing £2853; to keep things honest, our first-series XJ6 is the rarer 2.8, here fitted with a manual-overdrive ’box, which would have set you back an almost identical £2832.

Plans to replace the P5’s inlet-over-exhaust-valve 3-litre straight-six had been hatched soon after its 1958 launch.

Five- and six-cylinder versions of the P6 2000’s ‘four’ had been considered, but Rover MD William Martin-Hurst’s discovery of an abandoned V8 while visiting the General Motors Mercury Marine Workshop in Wisconsin immediately showed promise.

The Rover P5B’s armrest sports a table and cupholders

Designated ‘Buick 215’, the 3.5-litre, all-aluminium unit had originally powered Buick and Oldsmobile Y-body cars between 1960 and ’63, but a reversion by GM to all-iron engine castings had rendered it near-obsolete.

Seeing its ready-made potential, a hard-fought deal was struck by Rover to buy the rights and tooling for the engine, and by 1965 work had started in Solihull to adapt it for the P5.

While lacking the inherent smoothness of the P5’s existing 3-litre ‘six’, the V8 weighed a full 200lb less than the all-iron unit and only 12lb more than the then-new P6’s ‘four’.

New manifolds were developed to allow for better breathing and an increase in maximum revs from 4400 to 5200rpm, along with upgraded rocker shafts and a switch to twin SUs.

The Rover’s cabin has a stately air that is defined by the wraparound dashboard that curves neatly into the door trim

The unit was also an easy fit into the Rover’s engine bay, where, mated to a Borg-Warner Type 35 three-speed automatic ’box, it was mounted on the P5’s substantial front subframe.

With 151bhp versus the MkIII 3 Litre’s 134bhp, plus a lift in torque from 160lb ft to 201lb ft, the 3.5 Litre’s performance was in another league: 0-60mph acceleration dropped by more than five full seconds to 10.7 secs, and top speed increased from 100mph to 112mph.

Small wonder that the born-again V8 soon appeared in the P5B’s younger sibling, the 3500 (P6B), and then the all-new Range Rover – with the Morgan Plus 8 thrown in for good measure.

There’s little to tell the Rover 3.5 Litre Coupé from the six-cylinder P5, but the badging is a giveaway

Other than some rather snazzy RoStyle wheels, extra driving lights and different badging, when the 3.5 Litre P5B was unveiled at the ’67 Earls Court show, it was near identical to the outgoing P5 in almost every other respect.

David Bache’s elegant, restrained lines remained unchanged (they have a hint of scaled-down mid-’50s Americana – take a look at Virgil Exner’s Chrysler 300B for proof), as did the option of the Coupé model, which had first arrived in 1962.

Internally known as the ‘hard-top sports saloon’, its roof, with steeply raked wraparound ’screens front and rear, was 64mm lower than the saloon’s and was conceived with pillarless doors in mind – until it was realised that structural integrity would be compromised.

Also carried over was the P5’s front double wishbones and torsion arms, along with a live rear axle with semi-elliptics. Power-assisted steering was now standard.

The Jaguar XJ6 2.8’s smooth performance is in part defined by its short gearing

If the Rover was the P5 series’ final hurrah, the XJ6 would herald a new horizon for Jaguar.

The model was launched in September 1968, but work had started on Project XJ4 four years before.

Conceived as a ‘4-door E-type sports saloon’, there was to be nothing radical in the technical make-up.

It was a refinement of everything Jaguar did well, all wrapped up in a modern, svelte and crashworthy body, match-ready for the 1970s and fully compliant with safety rules, especially in the key US market.

‘Many a contemporary sports car would have struggled to keep up with a well-driven Jaguar XJ6 back in the day’

Two versions of the by then 20-year-old, double-overhead cam XK ‘six’ were available: a 2.8-litre, as in ‘our’ car, making 180bhp and aimed more as a tax-friendly offering for Europe (while theoretically appealing to fuel-conscious buyers elsewhere); and a 245bhp 4.2-litre range-topper.

Both engines were available with manual transmissions, with or without overdrive, or with a three-speed auto.

The iron-block XK engines, while still in their prime, had been around since the 1940s, but compared with the P5B’s relatively new, all-alloy V8, the XJ6’s underpinnings were in a different technological league.

Independent suspension included semi-trailing wishbones at the front and lower wishbones to the rear, with driveshafts as upper links, and both assemblies were attached to rubber-mounted subframes to minimise noise and vibration.

The Jaguar XJ6 2.8 uses a 180bhp version of the popular XK unit

There were disc brakes all round, the fronts with Girling three-pot calipers, plus a power-assisted steering rack for greater precision than the Rover’s recirculating-ball set-up.

Despite being developed on a fairly meagre £6million budget, the XJ6 was tasked with, in effect, replacing every other saloon in the range, including the Mk2, S-type, 420 and the unloved MkX.

The run up to its launch was a tumultuous period for Jaguar, which had sacrificed its independence in 1966 to merge with BMC and Pressed Steel (which was to produce the XJ6’s body), then became a sibling to rival Rover in 1968 when British Motor Holdings merged with Leyland to form BLMC.

The Jaguar XJ6’s ride is excellent, with little road or wind noise

It must have been some relief to founder Sir William Lyons and chief engineer Bob Knight when the XJ was launched to universal acclaim.

Not only did it offer outstanding value, with a launch price almost a third less than German would-be rivals, but it also raised the bar for luxury saloons in almost every area.

Autocar said: ‘Unbelievable value. The best there is. If Jaguar were to double the price of the XJ6 and bill it as the best car in the world, we would be right behind them. We see it as a new yardstick.’

The Rover P5B feels sure-footed at speed

Martin Robins has owned his Silver Birch over Admiralty Blue Rover Coupé for 16 years, before which it had been used sparingly by a Dundee-based family from new, accounting for its mere 51,000 miles – and it once appeared in a procession for the late Queen’s platinum anniversary, representing the year 1972.

It’s amazing what a difference the addition of some RoStyles and a pair of driving lights made to the Rover’s appearance, pumping up its ’50s styling quite aptly given its new-found powerhouse.

Contrasts don’t come much greater than with the XJ parked next to it, but, if anything, the P5B is more imposing: it exudes a luxuriant brutishness with which the Jag can’t quite compete.

The Rover 3.5 Litre Coupé’s huge rear armchairs

It’s clear why it became the favoured transport of Prime Ministers, from Wilson to Thatcher, albeit in saloon guise: there would have been few spaces more cosseting than the Rover’s rear, with individual, leather-trimmed bucket seats divided by a substantial armrest – complete with pull-down table and cupholders – thick Wilton carpets and the sheer opulence of separate controls between the front seats for heating and rear speaker volume.

The P5B was dubbed ‘the poor man’s Rolls’, but there was very little ‘poor’ about its interior.

Up front is one of the all-time classic dash designs. Curved around at each corner to meet the wood cappings of the doors, it is a masterful mixture of state-room elegance and first-class ergonomics.

Even divided by the richly trimmed transmission tunnel (with pull-out tool tray) the Rover feels spacious and practical, with a deep parcel shelf running the width of the car.

The Rover P5B has a pull-out tool tray under the dashboard

The driving position is commanding, its separate, high-set instrument binnacle underscored (on the Coupé) by auxiliary dials for temperature, charge, oil pressure and fuel.

Ignite the Rover’s V8 and its familiar subdued rumble fills the cabin.

You sit high, in part to see over the enormous, thin-rimmed steering wheel, inset with its chrome horn-ring.

It takes a few seconds for the hydraulics to take effect on the steering, but thereafter the variable power assistance makes for easy low-speed manoeuvres.

Back-seat heater controls in the luxurious classic Rover

Throttle response is good, and the Borg-Warner ’box slurs away imperceptibly, but you need a positive action to engage kickdown.

For a near-60-year-old motor, the Rover P5B feels indecently quick across our rural test route.

It’s planted and stable, although uneven surfaces give its rear suspension the quivers and the ride quality feels quite nuggety for a luxobarge.

The steering is resolutely devoid of feedback and has some play just off the straight-ahead, but it has more substance during cornering than the Jaguar XJ6, which actually gives you the confidence to lean hard into bends, prompting mild understeer.

The Rover P5B’s V8 burble adds more than a little character

You would never accuse the Rover of being sporty, but its muted V8 soundtrack adds more than a touch of olde-worlde hot rod to its make-up.

The XJ6 is nothing of the sort. Lower, wider and cleaner of line, it is quite telling that Sir William Lyons’ vision of a sporting luxury saloon not only evolved through three series of the XJ6, but also extended well into this century, only finishing with the X350 of 2002.

A Series I XJ such as this, though, remains the purest exponent of that vision.

Neil Murray has only owned this manual overdrive 2.8 since last year and is clearly not afraid to use it, having covered 400 miles in the 24 hours leading up to our shoot.

More advanced suspension gives the Jaguar XJ6 2.8 the upper hand dynamically

Even so, the car still shows just 16,500 miles, with a good chunk of that accrued by this magazine nearly 30 years ago when senior contributor Mark Hughes drove it to Biarritz for a story in the June 1997 issue.

Like the Rover, this Jaguar XJ6 is very original, having had a repaint in its factory colour some years ago, and its minimal use can be seen and felt as you hunker down in its low-set driver’s seat.

Facing you is a well-ordered dash, with large dials for speed and revs, and a bank of five secondary clocks across the centre, with no fewer than 10 rocker switches below them.

Backlit at night, the fascia looks magnificent.

The Jaguar XJ6’s busy but orderly dashboard packs in the dials

It’s strange to see a manual shifter sprouting from the central tunnel of an XJ, but its chromed lever and chunky gaiter add to the car’s sporting vibe.

You only have to travel half a mile in the Jaguar to realise how revelatory it must have been in its day.

Objectively, it has the Rover licked in almost every way – steering aside.

The rack is even lighter than the P5’s when parking, but while it gains heft with speed, and is faster-geared and keener to turn in, its featherlight nature means you can’t engage with the car quite as you’d like.

The Jaguar XJ6 2.8 has a sculpted bench in the back

That’s a shame, because the Jag’s dynamic repertoire is immense: it rides superbly, soaking up imperfections with ease and filtering out much of the suspension noise.

It feels stiffer than the Rover, and general levels of wind and road noise are lower.

The 2.8-litre ‘six’ is also smoother, if not as characterful as the P5B’s V8 when extended.

The four-speed manual is a delight: quite slow, but positive and well-oiled. There’s some gear whine in the intermediate ratios, but overall it’s a happy union between engine and ’box.

The Jaguar XJ6’s period radio

Accelerate briskly and the Jaguar XJ6 feels as quick as the Rover P5B to 60mph, but this is due to short gearing, not excess torque, which is perhaps this drivetrain’s greatest bugbear: in top it barely manages 17mph per 1000rpm.

Even with the overdrive engaged, the engine will be spinning at 3700rpm at 60mph.

None of this spoils the experience on a fast, twisty road, though: it feels biddable and composed, with hardly a trace of understeer.

I’d wager that many a contemporary sports car would have struggled to keep up with a well-driven XJ back in the day.

The Jaguar XJ6’s simple rear ventilation controls

Many years ago I owned both of these cars at the same time, although my Series I XJ was a 12, not a 6, and my 3.5 Litre Coupé was more Isopon P38 than Rover P5.

But what drew me to them as a 20-year-old still holds true.

The Jaguar XJ, regardless of engine size, was one of the best-resolved driver’s saloons of its day and remained so for many years after.

The Jaguar XJ6 2.8 has a manual shifter with an overdrive switch

I wouldn’t argue with anyone who felt that its design – aesthetically and functionally – was superior in every way to the P5B’s.

But just occasionally you’re entitled to make irrational choices.

That I am still as entranced by the Rover 3.5 Litre Coupé’s shape, its punchy V8 and the majestic way it drives down the road all these years later means it has been added to my bucket list of classics to buy sooner rather than later.

Images: Tony Baker

Thanks to: Robert Hughes; British Motor Museum

Factfiles

Rover 3.5 Litre Coupé

Sold/number built 1967-’73/9099
Construction steel monocoque
Engine all-alloy, ohv 3528cc 90° V8, twin SU carburettors
Max power 151bhp @ 5200rpm
Max torque 201lb ft @ 2750rpm
Transmission three-speed Borg-Warner Type 35 automatic, RWD
Suspension: front independent, by wishbones, torsion bars, anti-roll bar rear live axle, progressive-rate semi-elliptic leaf springs; telescopic dampers f/r
Steering power-assisted recirculating ball
Brakes discs front, drums rear, with servo
Length 15ft 7in (4750mm)
Width 5ft 10in (1791mm)
Height 4ft 10in (1473mm)
Wheelbase 9ft 2in (2807mm)
Weight 3500lb (1587kg)
0-60mph 10.7 secs
Top speed 112mph
Mpg 17
Price new £2853
Price now £15-40,000*

Jaguar XJ6 2.8

Sold/number built 1968-’73/98,527 (all SIs)
Construction steel monocoque
Engine iron-block, alloy-head, dohc 2792cc straight-six, twin SU carburettors
Max power 180bhp @ 5150rpm
Max torque 150lb ft @ 4250rpm
Transmission four-speed manual, optional overdrive, or three-speed automatic, RWD
Suspension independent, at front by wishbones, coil springs, telescopic dampers, anti-roll bar rear rubber-mounted subframe, lower wishbones, radius arms, twin coil spring/damper units
Steering power-assisted rack and pinion
Brakes discs, with servo
Length 15ft 9½in (4813mm)
Width 5ft 9¾in (1770mm)
Height 4ft 6in (1371mm)
Wheelbase 9ft 4¾in (2865mm)
Weight 3389lb (1537kg)
0-60mph 11 secs
Top speed 120mph
Mpg 15-18 (est)
Price new £2832 (1972, manual o/d)
Price now £8-20,000*