The Jensen Interceptor was a uniquely British, and super-cool take on the typical GT car of the late 1960s.
Clothed in a beautiful Italian body and powered by US V8 muscle, this was a car capable of trading punches with the cream of the supercar crop. Keith Adams tells the first part of its story.
Interceptor: Putting the Grand into Touring
The 1966 British Motor Show was hardly a classic. Family car buyers might have come away wondering if they would ever tell the show’s star debutantes, the Ford Cortina and Hillman Hunter apart, but there was no doubt that the Jensen Interceptor stood apart from everything else on the road. It made a huge impact that would resonate for years to come…
Interceptor was not a new name. The fledgling firm of Jensen had used it before the last war, and revived it afterwards for its 1950 cabriolet model powered by a 4.0-litre Austin A135 engine. In 1954 that Interceptor was replaced by the elegant 541, which became the 541R, before being replaced by the striking glassfibre-bodied CV8 in 1963.
The heart of the CV8 concept would also be the starting point for the next Interceptor, for both cars shared one of the then-new breed of big and powerful American V8s. It was a formula which was becoming popular elsewhere (with Iso in Italy, Facel Vega in France and Bristol in Britain) and Jensen’s choice was the Chrysler 5.9 litre, which came complete with three-speed Torqueflite automatic transmission.
Conventionally engineered, brutish power
The CV8 chassis could hardly be described as adventurous, even by the standards of the time – there was double-wishbone suspension at the front, and a live axle at the back located mainly by massive dual-rate leaf springs located with the help of a Panhard rod and some thoughtfully-located dampers.
The CV8 was quick by the standards of its day, though, with contemporary road tests crediting it with a maximum speed of more than 130mph and a 0-60mph time of about 8.0 seconds. There were few problems about stopping either, as the CV8 was one of the first production cars to have disc brakes all round. Its handling was also highly praised by the road testers and, compared with the 541, it benefited from the improvement in weight distribution thanks to the compact V8, which was installed well aft in the fabricated steel-tube chassis.
The testers of the day fought shy of criticising the quality of the bodywork, but its shoddiness was there for all to see. For such an expensive car – the CV8 cost £3400 in 1963 – it suffered quality problems associated with glassfibre panel construction of the time, with the added complication of matching the finish to aluminium door panels. The obvious answer was to adopt a properly tooled steel body and, in due course, this was done. The result was the Interceptor.
Getting the Italians involved
For its new body, Jensen went to Vignale’s drawing board and the workshops of Touring of Milan, who produced a design which was exceptionally stylish. The massively curved rear window was ahead of its time, influencing cars such as the Porsche 924, Citroën SM, Renault Fuego and 25 (the latter three, all being styled by Robert Opron), and several other cars. It was a styling feature that gave the Interceptor something of a timeless quality.
The overall balance of the body was superb and, unlike many rival GTs of the time, the Interceptor had four seats and a great deal of luggage space within a body measuring just 4.57m long.
Under the glamorous new body, the CV8’s underpinnings survived almost unchanged. The suspension remained unaltered, the wheelbase set at 105 inches, and the engine and transmission were also carried over, the former being a 6.2-litre version of the Chrysler V8, which had been slipped into the CV8 during 1965. However, there was no sign of the four-speed manual gearbox which Jensen had offered on the CV8 for an extra £100.
With the Chrysler’s claimed 330bhp (probably nearer 280bhp in reality) the Interceptor could hardly be anything but fast. It had, though, gained substantially in weight with its new steel body welded onto the existing chassis. Since the chassis was stiff enough, the Interceptor chassis-plus body was exceptionally robust – but the penalty was an extra 152kg of kerb weight over the CV8.
It is doubtful whether the Interceptor was any more aerodynamic than the CV8, and it is not surprising that the new model could not match the only set of reliable performance figures ever published for the CV8 in its 6.2-litre form (Autocar‘s 1965 test credited it with 0-60mph in 6.7 seconds, and a 14.6 second quarter-mile).
Even so, the early Interceptor would easily exceed 130mph and reach 60mph from rest in 7.3 seconds, going on to 100mph in around 20 seconds, even if it wouldn’t see which way a Jaguar E-type went.
What the testers said about the Interceptor
Those early Interceptors were an interesting mix of ancient and modern in several respects. On the positive side, they inherited the Salisbury Power-Lok limited slip differential which had been introduced on the CV8, and also the Armstrong Selectaride variable rear dampers.
On the other hand the rack-and-pinion steering didn’t have power assistance: Motor described it as ‘pretty heavy and lethargic’ which is restrained comment indeed when discussing a £3700 car weighing 1676kg. The magazine recommended lightening the steering by raising the tyre pressures from the standard 24psi all round to 36psi front and 48psi rear, a trick which was possible with the standard crossply Dunlop RS5s fitted.
Overall Motor was impressed, ‘the figures show what a tremendous performance this latest Jensen has but they do not really convey the absurd ease with which 325bhp thrusts the big car up to 140mph, nor the imperceptible pause as one gear slips into another in the uncannily smooth automatic gearbox.’
Motor was quite happy with the powerful Jensen’s handling too, ‘Whatever understeer the car normally has can be adjusted or overruled with the throttle, almost regardless of what gear you are in. Such roll-free response, together with a 50:50 weight distribution, splendidly progressive breakaway of the tyres on the limit, and enormous feel in the steering encourages brisk cornering,’ its road test concluded.
A question of gearing
One of the problems affecting the Interceptor’s performance was the question of gearing. Although the Chrysler V8 produced plenty of torque, peak power was reached at 4600rpm. Even with the big wheels and tyres, the direct drive top gear of the Torqueflite was good for only 25.6mph per 1000rpm with the highest readily available final drive.
Since the red line was set at 5100rpm on the Interceptor’s rev counter throughout the model’s life, this meant any road tester who admitted to exceeding 130mph had overrevved the engine. In fact, there was a tacit understanding that the redline could be ignored in top gear, and most of the published maximum speed figures correspond to about 5400rpm.
However, at this stage, the big V8 was beginning to sound very strangled, and there is no doubt that with a higher final drive – or an engine with improved high speed breathing – the car would have been considerably quicker. A Jensen Hemi would have been fast indeed…
It might also have been more economical, since the extra weight didn’t help: Motor‘s first published overall fuel consumption for the Interceptor was 11mpg, and things did not improve. Indeed, one of Jensen’s early developments was to increase the car’s fuel capacity from 16 to 20 gallons to answer criticisms of limited range.
Four-wheel drive and anti-lock brakes
There was more to the new Interceptor than a pretty body, though, because Jensen then announced its intention to building a version equipped with Ferguson Formula four-wheel drive alongside the standard model. Harry Ferguson had created tremendous interest at the time with his ingenious system with its torque-splitting centre differential, and Jensen jumped at the chance of making the Interceptor into a uniquely capable and attractive vehicle 14 years before the launch of the Audi Quattro.
Remarkably little work was needed to accommodate the new system: it was stretched by 10cm in order to fit the centre differential while retaining the standard rear propshaft, and to avoid compromising cabin space. The addition of a second pair of louvres in the front wings, just ahead of the scuttle line, were the biggest visual giveaway.
The FF system worked extremely well, giving the big car amazing traction and extremely safe handling. Some testers had more doubts about the Maxaret anti-lock braking, understandably perhaps in view of Autocar‘s finding that the system had a cycle time of 2-3 seconds. It also caused pulsing of the brake pedal and appeared to limit the best achievable stop to about 0.9g.
Not a commercial success
Aside from that, there was a drop-off in performance caused by the extra losses in the other half of the transmission. Autocar found the maximum speed dropped to 130mph, and the 0-60 mph was up to 8.4 seconds. Fuel consumption also suffered slightly (in part, no doubt, because of the extra fast-driving confidence that came with the FF system.
The biggest drawback of all, in most buyers’ eyes, was the price which was set at £5340 compared with the £3743 of the Interceptor. Had the FF been more visually distinctive it might have been more successful, but as it was, too few buyers valued the advantages of four-wheel drive sufficiently to spend all that extra money without anything visual to show for it.
The result was that, while Interceptor production eventually ran well into four figures, only a few hundred FFs were built and eventually Jensen withdrew the model, despite its technical success and excellent handling.
Adding more model derivatives
There were, of course, other directions in which the Interceptor could be and was developed. In 1969, the company tried to boost the car’s image by offering the Director, a version equipped with an array of communication and business equipment for the ultra-senior executive on the move.
To some extent this was rather a forlorn hope because, while the Interceptor was admired for its silence as much as its stability and performance, it was regularly slated for not having enough room in the back. The seats looked attractive at first glance, but practice soon showed they were too close to the floor (to ensure adequate headroom) and that kneeroom was at a premium.
Making it faster… and thirstier
It made more sense to make the Interceptor into an even higher-performance vehicle. Jensen no doubt looked longingly at the Chrysler Hemi but settled instead for a less wild solution: a bigger, better-breathing engine. The new Chrysler V8 was slightly bigger in bore and much longer in stroke than the 6.2-litre, and its displacement had risen to a massive 7.2 litres.
In its ‘performance’ form it was fitted with three twin-choke Holley carburettors, the centre one connected to the throttle pedal, the others operated by vacuum links from the inlet manifold. Since there were six chokes, the whole arrangement was known as the ‘six pack’ and the new Interceptor version was christened the SP for its launch in 1971. The most obvious visual clue to its performance were the additional cooling vents on the bonnet (below).
The bigger engine delivered 330bhp, which Jensen claimed was 55bhp more than before. But the power peak was still only 4700rpm, and the company resorted to a 2.88:1 final drive to ease the maximum speed limitation.
According to Autocar the SP was the quickest of the Interceptor series, with a 0-60mph time of 6.9 seconds and a 0-100mph of 16.8 seconds. The maximum speed was 143mph. Impressive though the SP’s performance was, the six-pack was not a happy arrangement because the transition from one set of chokes to all three was considerable and sometimes abrupt.
In the years up to the SP’s introduction at the 1971 Motor Show, the Interceptor had been steadily updated. Power-assisted steering had arrived, followed by 70-series radial-ply tyres on alloy 6.5-inch rims. Air conditioning had also been made standard, and the price had risen accordingly. There had been one minor facelift for 1970, with a repositioned front bumper and a few internal changes sufficient to warrant a change to MkII designation.
With the arrival of the SP, the companion Interceptor was again given some minor changes in appearance, the most notable being new cast-aluminium surrounds for the headlamps, and the incorporation of the side repeater flashers in the side grilles. Under the skin, more significant changes were the introduction of centralised locking and ventilated front disc brakes. In this form, the Interceptor became the MkIII (below).
Out with the FF, in with the SP
The FF did not long survive the arrival of the SP, the last car emerging from the factory in December 1971, bearing the chassis number 328: a sad commentary on the need to make high technology affordable as well as effective. What nobody appreciated at the time was that events were looming which would soon bring an end to Jensen itself.
For the 1972 model year, though, the Energy Crisis was still in the future. The Interceptor and the SP continued in production, to the extent that their chassis numbers came from a common series. In the 1974 model year, after the SP had been discontinued, its highly-individual bonnet vents were offered as an optional extra on the standard Interceptor.
In the meantime some standardisation was achieved with the fitting of a detuned version of the 7.2-litre engine to the Interceptor from July 1972 onwards. The bigger-engined Interceptors carried a letter J on their rear panels (the 7.2-litre engine being Chrysler’s Series J unit). In non-SP form, the J engine had a low enough compression ratio – of 8.2:1 – to operate on two-star fuel, and it still produced 280bhp.
Opening up to new markets
Despite the heavy design and development workload associated with the Jensen-Healey, the West Bromwich team still sought other ways of extending the Interceptor range. Even when 1973/74 brought higher petrol prices and the threat of petrol rationing, one of these projects was so near completion that it was proceeded with anyway, to emerge in March 1974 as the Interceptor Convertible (above).
The Convertible was a welcome addition to the range in one way, because the SP had been discontinued in October 1973. The company sought to exploit the almost complete lack of a big convertible in the British and European markets.
The conversion of the Interceptor was straightforward, since that hefty and essentially self-supporting chassis frame was already there. All that was necessary was to trim off the roof, fit a sill-frame and attach the massive hood complete with its power-folding machinery.
The resulting car weighed only 36kg more than the SP, so its performance remained extremely good: although by now road testers were paying more attention to redlines, and Autocar achieved a rev-limited maximum speed of 126mph, and 0-60 mph time of 7.6 seconds.
Succumbing to the inevitable
Jensen’s redesign of the original Vignale shape was reckoned highly successful, except for the way the hood folded down onto the rear deck rather than into a well, making the car look humpbacked. It did mean the car retained most of the luggage space and the two rear seats. It is a commentary on the way prices moved in the 1970s that the Interceptor Convertible listed for £9682.
Mere survival was becoming more of a struggle for Jensen but a further model was added to the range for the 1976 season in the form of the ungainly Interceptor Coupé (below). In effect this was a Convertible in which the hood was replaced by a fixed ‘glasshouse’ with tinted glass roof and quarter-panels.
Presumably the idea was to appeal to anyone who failed to find the original fastback shape unattractive (and possibly also to use up some of the slow-moving rear-end panels from the Convertible). In the event, not a lot more was heard of the Coupé and, indeed, little more was heard of Jensen other than the fuss which surrounded its liquidation.
And so, to the end… of Part One
The Interceptor itself can hardly be blamed for Jensen’s demise, which had much more to do with the weight of investment in the Jensen-Healey project and a determination to do well in the American market with a highly specialised car.
Throughout its life, the Interceptor was praised consistently, and rightly, for its performance – and the lack of apparent effort with which it was delivered. Its stability and handling were equally admired, and so was its refinement: it was, in its day, one of the quietest cars in which to ride.
Vignale’s body shape never failed to excite admiration. Criticisms were mainly confined to the lack of rear seat space, and the horrific fuel consumption (Motor‘s final road test of an Interceptor MkIII, run in 1975, credited the car with just 10mpg overall, which could hardly have done its sales prospects much good). The last Interceptor emerged from the West Bromwich factory in September 1976.
Rebirth would come
That was not quite the end of the story, though. The Interceptor was too good a design to die. Some survivors of the Jensen crash eked out a living by buying the remaining stock of components which was, as it happened, considerable – and by selling them and undertaking repair and restoration work. This business grew into Jensen Cars Ltd.
Cropredy Bridge Garage also stepped in to keep the flame alive. It was set up when Jensen Motors was still making new Interceptors. The business then offered service and maintenance for both current and older Jensen cars. Throughout the 1980s and ’90s, it became the UK’s primary centre of Jensen expertise – ending up selling restored and recreated Interceptors.
There have subsequently been a number of attempts to relaunch Jensen and the Interceptor which we’ll go into much more detail about in a follow-up story.
Photos: Alan Kenny
Jensen Interceptor specifications
Jensen Interceptor UK price when announced: £3742
ENGINE: Front, longitudinal Type: Water-cooled V8 with cast iron block and heads. Two valves per cylinder operated by single camshaft.
Engine capacity: 6276cc
Maximum power: 325bhp at 4600rpm (SAE gross)
Maximum torque: 425lb ft at 2800rpm (SAE gross)
Bore x stroke: 108mm x 86mm
Compression ratio: 10.0:1
Fuel supply: Single Carter four-barrel carburettor
Ignition: Mechanical with coil and
TRANSMISSION: Rear-wheel drive, three-speed automatic Chrysler Torqueflite
Front: Independent with twin wishbones and coil springs
Rear: Non-independent with live rear axle located by semi-elliptic leaf springs and Panhard rod
STEERING: Rack and pinion
BRAKES: Dunlop discs front and rear, servo assisted with divided hydraulic circuit.
WHEELS AND TYRES: Type: 5J steel wheels with Dunlop RS5 6.70 X 15in tubeless crossply tyres
BODY/CHASSIS: Tubular steel chassis with unitary steel coupé body
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