This report was taken from the Vauxhall Autosport Supplement from 1990
Is the Lotus Carlton the fastest four door saloon car in the world, or is its' 176mph maximum pipped by the Alpina B10 Bi-Turbo? Frankly, who cares? In everyday use there's nowhere that sort of performance can be exploited in complete safety, not even on the autobahn where the lack of speed limits on certain sections, the presence of other, slower, traffic means that attempting such outrageous maxima is simply not possible.
Vauxhall itself makes no claims for the Lotus Carlton's top speed other than to say that the aim was to create a car, still recognisable as a Vauxhall, that explored the outer limits of acceleration, ride and handling. "High speed is an outgrowth of it", is the official line.
Press harder and Vauxhall will reveal that an independent test clocked the car at Nardo in Southern Italy at 176mph. . . but the subject is quickly changed, Vauxhall, in fact, is quite happy to quote all sorts of performance figures except that one. Favourite is the 0-60-0 time of 8.5 secs. Nothing to do with train spotting, it's how long it takes the car to go from a standing start to 60mph and back to standstill again. The message's clear, just don't mention top speed again.
The Lotus Carlton is based on the much acclaimed Carlton 3.0 GSi 24v, but turning it into the fire breathing Lotus Type 104 has involved major redevelopment of the engine/drive train and the chassis - both areas in which Lotus is an acknowledged master.
The engine may retain the basic configuration of the GSi, but actual changes are legion. For a start, by increasing the stroke Lotus has upped the capacity from 3-litres to 3615cc, while the block is far stiffer than the standard offering, to withstand the enormous amount of power and torque developed by Hethel's heroes.
The original objective had been to extract 100bhp per litre from the engine - in the end, the final figure betters even that goal. The Lotus Carlton develops 377bhp at 5200rpm and an enormous 419lb ft of torque at 4200rpm. Even more impressively, almost 75 per cent of that is developed as low as 2000rpm.
To say that Lotus has achieved these phenomenal figures just by adding a pair of small Garrett T25 turbos to the package would be oversimplifying the case somewhat. True the twin turbos - smaller turbos react quicker ones to overcome the dreaded lag - are central to the power hike, but only meticulous development work has been able to ensure that the engines can cope.
The complete package includes new pistons, connecting rods, and crankshaft, a reinforced cylinder block, a new induction system, cooling manifold and throttle bodies, better cooler and better oil flow. The pistons are oil cooled from beneath and the twin turbos are charge-cooled, the Lotus name for its liquid intercooling system. Naturally major changes have been made to the electronic management system and, equally naturally, the Lotus Carlton features two closed loop catalytic converters.
Thanks to the cats, the Lotus Carlton has to run unleaded fuel and optimum performance is achieved with 98 octane 'Super' unleaded. It will run happily on 95 octane premium unleaded but the power loss is said to be around 40bhp.
Handling all that power and torque is a beefed up clutch and ZF's six speed gearbox, originally designed for the Chevrolet Corvette ZR1. The gear shift simply tacks the sixth speed opposite fifth in an otherwise conventional 'H plus one' pattern. The rear is another GM part, this one being a modified Holden unit.
Class leading performance was the goal and certainly the rivals are hard pushed to match 5.2secs to 60mph from rest, 0-100mph in 11.5secs and that top speed of... oh yes, we said we weren't going to mention that again, didn't we.
To cope with that sort of power, you need bloody good brakes, and those on the Lotus Carlton come courtesy of Group C racing. AP, who developed the system for Lotus, use four pot racing calipers at the front, originally designed for Le Mans, on 330mm vented discs. Twin piston calipers on 300mm vented discs can be found at the rear, while the standard GM/Bosch anti-lock system is retained.
Chassis development is another example of myriad detail changes to a fundamentally sound design. The primary objective has been to control camber angles to create a car that handles as neutrally as possible. At the rear, an extra link has been added to the standard car's semi-trailing arm system and pick up points have been lowered. Twin tube dampers and progressive rate coil springs have been added and the geometry fine tuned by Lotus. Twin tube dampers can also be found at the front, along with the Lotus refined standard strut-type suspension. Wheels and tyres are massive 17in cotton reels shod with ultra low profile rubber - 45ZR tyres on the front, and 40ZR behind.
Just 17 Vauxhall dealers have been chosen to handle the sales and after service of the Lotus Carlton. But it was no easy task picking the right dealers. As Peter Batchelor, Vauxhall's Sales and Marketing Director, says: "Clearly, we could not expect every Vauxhall dealer to handle the Lotus as the volumes simply wouldn't make this feasible." Even so, more than 250 did apply to handle the car...
"In choosing the final 17, geographic location played a part, but far more important was the right attitude. We are not simply asking them to sell a car - I am expecting them to marry their customers! many potential Lotus Carlton owners will be coming from rival marques with legendary levels of customer service and attention. Our Lotus Carlton dealers will match or better that."
Vauxhall is also well aware that the performance potential of the Lotus Carlton might come as a surprise to some customers and, accordingly, included in the £48000 price tag is a day of high intensive driver training. The course, run in conjunction with the Institute of Advanced Motorists and the Jim Russell Driving School, comprises lectures in the theory of performance motoring followed by practical experience at the wheel of the driving school's own Lotus Carlton, all conducted in the safety of the Donington track.
"It's not compulsory to take the tuition." says Batchelor "but we expect the vast majority to take up the offer. Having done a similar course myself. I can vouch that it's a real eye opener...."
Although obviously something special, much of the Lotus Carlton's charm is that it is not a highly strung stallion waiting to catch out the unwary. And while it may perform like a Ferrari it comes complete with a most un-Ferrari-like warranty. As well as a standard 12 month unlimited mileage guarantee, there's a six year anti-perforation rust warranty and a three year / 70,000 miles mechanical breakdown insurance. Even servicing requirements are modest, with service intervals at every 9000 miles just like a Nova.
Modesty, however, is not one of the Lotus Carlton's strongest suits. One look at the menacing black-look paint scheme and the hardly discrete body kit and it's obvious the car means business. And, by god, it goes.
Let's deal with the irrelevancies first - top speed might well be almost 180mph but finding out simply isn't worth the bother. Rest assured the publicity around the car means everybody knows how quick it is so you won't have to prove it. The closest we got was a comparatively tame 140mph around the high speed bowl at the Lotus-owned Millbrook Proving Ground. G-forces on the bowl are such that sustained running at higher speeds, we were told, would cause the rear tyres to blow.
You can also forget sixth gear. At 100mph in top the engine is ticking over at 2200rpm, at lower speed you'll be close to stalling and acceleration is both leisurely and fuel inefficient. At 100mph in fifth the engine's turning over at 3400rpm, the twin turbos primed ready for action.
And while the Lotus Carlton is happy enough on a motorway, it really comes alive on A and B roads where its explosive acceleration, responsive handling and sheer grip are waiting to be unleashed. Overtaking, almost regardless of which gear you're in is over in seconds while the handling is as near neutral as it can be.
Despite all the rubber, the massive torque on tap means that the Lotus Carlton will oversteer when asked by an indelicate right foot. It does so smoothly and progressively, but discovering that is really only possible on a test track. No-one in their right minds would reach the car's limit on public roads.
That's the real joy of the car. It has the power, the acceleration and handling of a mid-engined supercar and none of the drawbacks. It will seat four in supreme comfort, is far easier to drive than the performance figures suggest and asks the driver to make no compromises. Visibility out is no problem, for example, there's room for luggage and it's not so wide that country lanes become off-limits.
One day, all cars will be this good. No, sadly, that probably won't be the case as the do-gooders and kill-joys will do their best to have cars like the Lotus Carlton banned just because of their top speed. One day all cars should be this good.
Creating the Lotus Carlton
It takes 150 hours to create a Lotus Carlton, to turn a mass produced Vauxhall into a hand finished Ferrari frightener. The starting point is a virtually standard example of the acclaimed Vauxhall Carlton 3.0GSi 24v.
There are just two alterations made to the Carlton on the production line at Rüsselsheim in Germany, before being sent to Lotus at Hethel in Norfolk. Two ventilation holes are pre-cut in the bonnet and the cars are painted in the pearlescent green colour, a shade unique to the Lotus Carlton. Green it is not, however. From most angles it looks black, from some it looks blue... but green, never! The cars are all runners when they arrive - it is a great deal easier to drive a car on and off a transporter than having to push it everywhere - but once they are safely ensconced in what used to be the DeLorean development shop, they are taken apart. All the trim is removed and the are seats sent away to be retrimming in the finest Connolly cow. The engines and gearboxes are removed, crated up and returned from whence they came and all the running gear is removed. And then out come the hacksaws... for turning a Carlton into a Lotus Carlton calls for some sheet metal surgery. To accommodate the new engine and gearbox some modifications have to be made to the floor pan and transmission tunnel, while to prevent the massive wheels and tyres fouling the bodywork, the wings have to be cut away, especially at the rear where the standard car has squared off arches.
While this work is going on, the engines are being built from new parts by a small team of engineers. Taking a leaf from Aston Martin's book, each engine is built solo by one engineer, though Lotus haven't yet adopted Aston's idea of putting a brass plaque with the name of the builder on each engine for posterity.
Once the body changes have been completed and the wind tunnel designed aero kit added, the engine and gearbox is mated with the bodyshell and the front and rear suspension assemblies hung into place. Then the trim - leather upholstery, suede-like panelling on the doors and liberal doses of rich veneer to door cappings and the gearlever surround - is fitted. After final checks, each car is then given a short shake down on Lotus' own test track before delivery to Vauxhall.
Over the next two and a half years a total of 1,100 Lotus Carltons will be created at Hethel, with 440 built in right hand drive for the UK market. Another 440 are being built for Germany with the remainder - 220 cars - sold in left hand drive form in other European markets. Why was the figure of 1100 cars chosen? Officially that's the number market research has indicated GM can comfortably sell in Europe. Unofficially, and given the time it takes to build each car, that's how many can be created before the next generation of Carlton is due to appear.
The timescale from computer screen to production reality is impressive - less than two years from start to finish. The concept was agreed by GM Europe and Lotus in September 1988. By January the next year the first engine had been built and two months after that, a full size mock up of the car appeared at the Geneva Show.
Testing of prototypes began in earnest in summer 1989 - and as the car had already been shown in public, elaborate disguises and subterfuge were not need which must have made life a little easier. Over the winter of 1989, 90 trips were made to the Arctic Circle for testing of not only the car under severe conditions, but also of some specially developed Goodyear winter tyres.
At the same time, durability tests were being conducted at Millbrook and by spring 1990 the pilot build was underway with the first full production rolling off the lines by the late summer. Now that the astonishing Lotus Carlton is a production reality what happens next is the question everyone is asking. Will we ever see a Lotus Calibra? At present neither Vauxhall nor Lotus is saying...
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