More power please

The deception of basing a low slung coupé on popular saloon car components — in this case the floorpan and much of the running gear of the bestselling Vauxhall — is almost as old as the motor industry. As long as the public are willing to pay more for less accommodation the practice will continue. Meanwhile, the European public certainly seems to be happy with Vauxhall and Opel Calibras in what has become a very tough European car market, keeping the German factory humming along on extra shifts to meet the demand of 70,000 Calibras per annum, rather than the predicted 35,000.

These are not figures to challenge those fast selling Ford coupés that everyone still seems to recall, the Mustang and its European Capri sibling, but the signs are that the Calibra is a creditable quality coupé. One that is influencing the way people regard General Motors and that will provide excellent profits for years to come.

Opel in developing a 1989 line of sleek Calibras that are also badged by Vauxhall for British sale, have not been so cynical as some of the commercial 'cut and shut' merchants, for the Calibra body is a genuine aerodynamic advance in its own right.

Russelsheim-based designer chief Wayne Cherry, the Indiana born American who spent so many happy years at Luton from 1965 onward, took some genuine risks in the creation of a machine that offers the best aerodynamic drag factor I can recall on current sale in the mass production sector; 0.26Cd. The impeccably presented dark metallic test car was not quite that slippery, owing to factors that we detail below, but it still slithered through the air with astonishing peace, credible rapidity (just over 130 genuine mph) and an average 26.5 mpg.

All this courtesy of a comparatively lowly 150 bhp that had to go through a 90 degree engine to transfer box skew in the power train, and a number of extra gear sets, in this 4 x 4 application.

Vauxhall started selling a 2-litre Calibra range only in front-drive earlier in 1990, comprising an 8-valve/115 bhp at £14,995 or the very effective DOHC 16-valve of 150 bhp and £17,595 cost. The test car is the latest 4 x 4 development of that 16v theme, which has been on sale since October 1990 in Britain at a current cost of £19,245. As one would hope, standard equipment is comprehensive and embraces electronic anti-lock braking, catalytic convertor (cheaper unleaded grades only); quartet of disc brakes; central locking and power assistance or operation for steering, side glass, mirrors and steel sunroof.

Our evaluation had to concentrate most upon the question of value versus driver pleasure and security, for the front-drive 16v Calibra (like its Vauxhall Cavalier GSi brethren) is perceptibly faster on two driven wheels. Knowing that GM (or rather, their consultants at Swindon Racing Engines) can extract up to 220 reliable racing or rallying bhp, we might have hoped for extra horsepower in the 4 x 4 version to offset its 221 lb weight handicap, and the power losses inevitable in all wheel-drive engineering.

Technical Analysis

The Cavalier name has been with us in Britain since 1975, but it was the 1981 adoption of front-drive and the current 1988 body that acted as direct ancestors to the creation of a Calibra coupé. The affable Wayne Cherry recalled, "In 1987 we started serious work at Russelsheim on a coupé that would use the Cavalier floorpan (including the 102 inch wheelbase) and much of that car's running gear. Today we design studio people work alongside engineers who prove the aerodynamic and stability worth of our work in parallel to the creation of a new shape."

One might fear that the more imaginative styling ideas were then immediately consigned to the electronic Computer-Aided wastepaper basket, but the expat American confirmed: "We started with one big aerodynamic advantage; no need to seat three abreast at the rear, which meant we could tuck in the rear panels in a manner that is not possible in a family sedan."

The Calibra started life as "Around an 0.28Cd outline, but it did not take too much work to return the 0.26 of the base model," reported Mr Cherry. Even a casual onlooker must be impressed by the flush glass attention to detail, including ellipsoidal (running on the principles of a cinema projector) headlamps that have only 2.75 inches vertical depth and that lithe line to the rear panels, uncluttered by added spoilers.

The body side sill extensions are "quite important" in allowing the wheels to be shrouded, so that the use of 205 section tyres on this derivative does not in itself boost the basic drag factor from that much quoted 0.26Cd. We are told it is actually the 16-valve engine's thirst for air beyond that of the single camshaft/8-valve that makes the biggest aerodynamic difference, the extra orifice between headlamps boosting the test car to an 0.29Cd, which is still in advance of most opposition.

Technically speaking the aluminium head 16-valve engine and DOHC valve gear with low service hydraulic valve gear adjustment should attract our attention next. Yet this Opel "all-square" (86 x 86mm) 2-litre is such a proven force in road and track trim that it does not often get the recognition it deserves.

In the writer's estimation the German GM unit is simply the best sporting 2-litre four in the world, combining a marvellous spread of torque (belying that 4800 rpm peak) with an appetite for life at its 6900 rpm limit that is unmatched.

It is a touch noisy to compete with BMW and Honda when it comes to plusher applications of 16v/2-litre technology. Yet, having driven it at every stage from the fuel injection production 150 bhp to carburated Vauxhall Lotus single-seater and competition injection 220 bhp trim (within Group A Astra GTE rally and race cars) I feel confident in a personal recommendation on the basis of reliable and accessible power.

If there is a criticism within the Calibra installation, it is that they should have uprated the 4 x 4 derivative another 20 bhp (as Ford did in the switch from rear drive Cosworth Sapphire to 4 x 4) to offset power losses and weight gains. Full marks for the catalytic convertor-only specification on the Calibra line, none of the initial glitches in carbon canister fuel smells now evident, and the sparing use of 95 RON octane unleaded a welcome bonus in these expensive petrol pump times.

The 4 x 4 installation is also inherited from the Cavalier (2000 GSi 4 x 4), but still deserves description. GM drew on the Austrian expertise of Steyr Daimler Puch (SDP), who briefed to keep costs within bounds and allow maximum use of existing front-drive components. The Cavalier/Calibra floorpan pressing has to accommodate the rear-drive transfer transmission, three-piece propshaft and a hybrid rear axle/suspension layout that draws on Cavalier, Senator and Carlton components.

A compact step-up gearbox is squeezed within the standard transaxle casing, its input shaft connected to the primary crown wheel, which rotates at drive shaft speed. Hypoid gears with primary ratios of 1:1.5 then deflect drive through 90 degrees (a right angle). That 'about turn' is followed by a trio of planetary gears that bear a ratio of 1:2.47 when the epicyclic gear set has its annulus electronically commanded to lock.

The overall compound ratio is therefore 1:3.7, inverse to the (in round figures) 3.7:1 final drive ratio. After all that, I am simply astonished the weight penalty was only 221 lbs and that performance was as vigorous as that measured, but there is more.

GM required a 'fully variable' power split, front to rear. Research showed that premium first gear acceleration was obtained with 73:17 front to rear torque percentage split, whilst loose gravel demand a percentage split of 40 per cent at the front and 60 per cent at the rear.

The faithful Viscous Coupling (patented by Ferguson but manufactured under licence overseas today) was placed between the planetary gear set and the three-piece rear propshaft. An additional electronic control unit is also provided to hydraulidally lock the annulus of the hydraulic; when unlocked the Calibra (or Cavalier) is placed in front-drive only, and that was the embarrassing state in which initial Cavalier 4 x 4 machines were often operated after a fault developed in the first batch to reach Britain.

The Bosch ABS system is a conventional one, for GM have opted to have the free-wheel in operation under braking; primarily to avoid rear end lock up on slippery surfaces. The hydraulic disconnection system shares power delivery with the hydraulic pump that serves the standard power steering. When the system has to operate in 2WD, locks into permanent 4WD a warning light is activated.

Cabin

The cockpit is as patchy with contradictions as the seats are in their flecked greys and bolstered cloth outlines. The driving position is absolutely first class, a real 'front row of the circle' feeling imparted by the steeply sloping bonnet, but reversing is not so easy with much hidden by the equally steeply raked rear window. We also objected to losing a startling amount of front occupant footwell room to the intrusion of four-wheel-drive components, the carpeted lumps and bumps more reminiscent of an after-market conversion than a World class multinational product.

Plastic qualities, trim, fit and finish all show that the largest of mass producers has learned that buyers demand far more of their surroundings these days, but the cockpit lacks the overall sparkle that one might hope for from a sporting coupé. The four-spoke steering wheel is a pleasantly padded affair, swiftly adjustable via the unique GM action. The black and white 140 mph speedometer and 7000 rpm tachometer sit within instrumentation that is a model of clarity. Yet little information is vouchsafed beyond water temperature and the contents of the 60 litre/14 gallon fuel tank.

There are some detail additives; the sunroof electrically retracts outside the roof (à la Honda CRX) and the power-operated side windows do not ingest much fresh air as their surface area is severely curtailed by a fixed front quarter pane. Useful standard equipment also extends to power-operated and heated door mirrors, split and folding rear seats that offer quite reasonable accommodation by coupé standards (above the usual '+ 2' norm) and an anti-theft alarm that enforces its intentions with a siren and "acoustic pattern detectors to interrupt the starter circuit".

In the modern manner the controls are unremarkably light and cooperative. The gearchange was notably excellent, although it was possible to miss the second to third march across the gate in normal road use. The clutch on our example did not like standing starts for performance figures and clambered toward the top of its travel by the close of testing. Worthy of commendatory comment were those slim headlamps. Supported by auxiliaries they exhibited plenty of tarmac on full beam and a sharply defined cut-off of unusual intensity and usefulness.

Overall, the cockpit of the Calibra is an efficient rather than inspired dwelling place for the keen driver. Noise levels are remarkably low, albeit you can summon your own choice of uproar from a Philips security coded radio/cassette player and Setuplet speakers.

Action

An unusually broad cross section of drivers appraised the Calibra, including one of our younger photographers, a company director from outside the motoring world and two of our employees with circuit racing experience. The consensus was unusually precise; "Very nice, very easy and peaceful to drive, but there is not much excitement and it needs a bit more power."

A GM chassis engineer would probably feel that means a job well done, for when a 130 mph coupé is dismissed as unexceptional, it is a sure sign of a capable chassis, especially when the drivers ask for more power.

To underline the point, the Vauxhall's smooth glazing and curvaceous lines slid through the Millbrook air so easily that we were able to carry on a conversation with precise instructions at maximum speed. The Calibra remained 'rock steady' at 130 mph and could be placed precisely if an alternative course was desired, even at this velocity.

That was the Good News from German chassis development: extreme stability even at maximum speed. The less attractive dynamic facets include a restless and jiggly ride over British B roads, although it must be said is improved in the 4 x 4 version in comparison to the front-drive models. As I understand it, this could be laid at the door of gas damping and bushes, but it is worth remembering that all Calibras feature notably stiffer front springs and the rear 'miniblock' helper springs are also noticeably stiffened.

The overall effect is to provide an inert but accurate, smooth and high-speed road response (the ride does get better as you travel faster, even on poorer quality surfaces), but both driver-pleasure and comfort should be improved if you picked the front-drive Calibra over cars such as the Corrado. In the case of the 4 x 4, it mostly simply gets on with the job of tackling any cornering radius with a degree of adhesive understeer that is efficient but unrewarding. Should you decide to assess the quality of the Vauxhall chassis over lightly travelled roads, or seek maximum standing start adhesion on less than perfect surfaces, there are some relevant setbacks. We were quite surprised at the amount of tyre slippage allowed by the 4 x 4 system away from a dry standing start, and the GM-SDP conversion is not the best we have tried for sheer grip. Perhaps it spends too much time apportioning power front to rear?

The ABS does not like differing surfaces much and the ultimate stopping power of the quadruple discs left us unimpressed. It is not that the centre pedal fades, more that the retardation rate in harsh use simply does not seem to match the demands of a slippery and heavy body. It is not dangerous, but even a 38,000 mile Ford Cosworth felt a lot more reassuring in this department.

Conclusion

The statistics of Calibra 4 x 4 motoring are not exceptional today, especially by comparison with its 16-valve front-drive sibling, but figures do not reveal the heart of the Calibra 4 x 4 argument. There are the usual stability benefits of 4WD, and this would be the only major reason for selecting a 4 x 4 Calibra at £1650 more than the equally powerful Calibra 16v front-drive model. It is certainly pleasant to be rid of the side effects of powerful front-drive (although the Calibra is now a lot better behaved than the original 150 bhp Cavalier 2000 GSi), but the deadening of performance and worthy chassis competence are not sufficient encouragements to purchase, unless a company is paying the difference.