Test-drive Chevrolet Corvette Coupe C4

Theoretically, you can buy a left-hand-drive Corvette from any of three special GM dealers in this country, or else you must go as we did to Belgium. When the ’84 Corvette C4 was announced a year ago, it was clearly aimed on its home market at the increasingly successful imports from Ferrari, Jaguar and Porsche — and at 29,200 dollars, it is clearly competitive. It would have been on the Continent too, but for the dollar’s return to strength, which puts the Belgian price up to 1,686,500 francs basic (£21,620) or a total, including local taxes, of 2,243,045 francs (£28,757 at 78 Belgian francs to the pound).

The European specification Chevrolet Corvette Coupe C4 car has no catalyst, but retains the air pump. The suspension is normally GM’s much stiffer Z51 sports springing and damping — an option in the USA. An oil cooler is standard. GM’s published power output for the European car is 201 bhp (PS- DIN) — 148kW — at 4,200 rpm, with 289 lb.ft. of torque peaking at 2,700 rpm. The test car went as if those European horses were remarkably healthy, especially for an automatic. 

1. Signalling/cruise control stalk, 2. Steering column rake adjustment, 3. Bar graph speedometer, 4. Horn button, 5. Mileage (range/trip)6. Oil pressure/ temperature, 7. Bar graph fuel gauge, 8. Fuel consumption, 9. Coolant temperature/battery voltage, 10. Bar graph revcounter, 11. Overall mileage, 12. Function reset, 13. Range/trip mileage selector, 14. Oil pressure-temperature selector, 15. Instantaneous/average fuel consumption selector, 16. Coolant temperature /battery volts selector, 17. Radio/cassette player, 18. Heater/air conditioning controls.

Max: 142 mph 0-60 mph. 6.6sec 16.7 mpg overall

FOR: Tremendous performance. Superlatively smooth automatic. Good instrumentation.

AGAINST: Harsh ride. Very high road noise.

Performance

On first acquaintance, one of the things that strike one about this highly idiosyncratic machine is its somewhat heavy, unprogressively accelerator, which seems abrupt at first, although one gets used to it. The next thing that impresses one immensely is the nigh-perfect smoothness of its transmission, which changes up or down both promptly and sweetly, whether on part throttle or full-blooded kick-down.

With the 3.07 final drive (a 3,31 ratio is also available), fourth becomes near-ideally geared for the car to achieve its absolute maximum speed, assuming the 4,200 rpm power peak is correct. In relatively good weather (no more than 10 mph wind, and dry, if cold surfaces), the car recorded a rousing, most un-American mean maximum of 142 mph, with a best one way of 145, which correspond to 4,100 and 4,150 rpm.

Flooring the throttle pedal a shade before releasing the brake proved the best, for standing starts, around 0.1 to 0.2sec quicker over the first 10 mph than a conventional full converter stall start. The box’ changes up at maximum speeds of 36 mph (4,500 rpm) in first, 69 (4,600) in second and 99 (4,050) in third, so it is not surprising that over-riding these points with the selector, only helped slightly when raising the third gear speed. As the figures show, the Corvette’s acceleration is everything one might hope for from its, to our eyes, deliciously brutish-graceful looks. Putting it in a European context, at up to middle speeds at any rate, it accelerates faster than the previous generation manual- gearbox Porsche 928S last tested here, equals a normal automatic Aston Martin V8, and is only a shade behind an XJ-S. Its limited slip differential plus those hefty boots give it excellent dry road traction from a standstill, with only a modest amount of wheel spin.

There is nothing soft or ‘‘wet” about the Corvette, contrary to what the average European might expect from an American car. The maximum kick-down speeds are one illustration — set at 94 mph from top to third, 57 from third to second, and 24 from second to first, or at three quarters of the peak speed in each gear, which is reasonable. Its very capable engine is nicely docile, if not at all quiet, snuffling along in typical V8 fashion at a lazy 1,000 rpm and 35 mph, but kicking you lustily up the speed range the moment you wish it.

TECHNICAL FOCUS

By any standards, let alone American car ones, the 1984 Corvette is unconventionally made. Plastic bodywork has long been a Corvette tradition, but “Corvette Three” is notable for some unusual chassis and suspension parts. Its front-mounted, cast- iron-cased, hydraulic tappet OHV, over square 5.7-litre V8 has nothing radical about it, apart, mildly, from its twin throttle-body injection system which is electronically controlled.

The separate chassis is galvanized steel with a pair of box-section side members joined laterally by a variety of cross members, rendered in high strength mild steel. Down the middle of the car, joining drive unit to final drive, there is a large 3/1in.-gauge aluminium alloy channel on its side, its web pierced for lightness, and doing the job of a torque tube. More aluminium alloy is used at the back, in an elegant cast transverse girder-like piece carrying the final drive casing (also light alloy) on two wide-spread flexible bushes.

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Front suspension is double wishbone, with forged aluminium alloy as the material. The same 6061-T6 alloy is used for the forged toe-in control fifth links of each rear suspension and also for the bottom transverse links, of inverted T-section, plus the twin trailing links. The hefty fixed-length drive- shafts are aluminium alloy. Lode at the car’s springs, and you find transverse single leaves at each end, made of epoxy resin reinforced with continuous strands of glass fibre. Damping is conventional telescopic. The assisted rack and pinion steering has an aluminium alloy rack housing. The Australian Girloc brake callipers are also in light alloy, working on 11 1/2in diameter ventilated discs. The aluminium wheels are, for Europe, 8 1/2in. rimmed (American Corvettes have 8 1/2in. fronts and 9 1/2in. rears), shod with Goodyear’s very P7-recalling P255/50VR16in. Eagle covers.

In size, the strictly two-seater Corvette has near enough the wheelbase (96.2in.) of a Lotus Esprit Turbo, and the length (14ft 81/2in.) of a 928S. It is an inch under 6ft wide, which is not quite as gross as the Lotus or Porsche — and in spite of its iron engine, it weighs more or less the same as the Porsche, but has one third less power.

Largely aluminium alloy Corvette drive train bared, showing final drive girder supports (cast), pierced-web channel (pressed) acting as torque tube between final drive and gearbox, unequal length front wishbones (forged), and at rear, the huge fixed length drive shafts (behind rearmost toe-in control arms). – Transverse springs are glassfibre.

To most eyes refreshingly “dean” Corvette styling looks extra-purposeful on the move. Headlamps retract by rolling through 180deg. into bonnet.

There is a small amount of “shunt” — jerkiness from the engine and its mounts — on abrupt application of accelerator, as the converter lock disengages, but not when decelerating, thanks to the torque converter’s jerk-absorbing effect. The transmission selector suffers from the still not-uncommon fault of no detent “stop” between Drive and Neutral, so that if using the selector to over-ride the automatic change points, one must take care not to slip past Drive into Neutral. The cruise control provided works effectively if more noticeably than European ones when it is adjusting accelerator opening to correct the speed selected.

Economy

In the 1,062 miles of the test drive, the effect of a high proportion of flat out or fast running at just under 12 mpg is to pull the overall consumption mpg a good way down, to 16.7 mpg. Driven more normally, it isn’t difficult to achieve between 18 and 20 mpg, but the provision of an only 16.7-gallon tank does limit the range to between 250 and 320 miles or so. The tank brims slowly to deter complete filling of its anti-expansion-spill arrangement. We were not impressed with the bar-graph fuel contents display, because the liquid crystal bars are too many (17 including the zero one) and in spite of fatter ones for the quarters, too close and thus difficult to identify except when stationary.

Refinement     

Bluntly, the only refined things about the Corvette are its transmission — superb — and, a lot less impressive, its engine, of which you are always to a greater or lesser extent aware. From other aspects of itsbehaviour, it obviously has relatively little suspension linkage “rubber”, which gives it extremely high road noise, in both road-roar and bump-thump. The latter is very high, so that the banging generated by the closely-set divisions between concrete slabs on some Belgian autoroutes caused us to stop, fearing a puncture. Every rib in such a concrete surface is transmitted as noise, most faithfully. On smoother German autobahnen, road noise is not such a nuisance, but the hum of the engine is considerable from medium speeds upward, second only to bad wind noise. At above 100 mph, this is noticeably poor from the rear edges of the doors, and on the test car there was a marked juddering wind noise from the hatch, even though this was properly shut. The frequency of the door seal wind noise drops slightly if one switches on the roll-over headlamps, as it does on other fast cars with pop-up lights. The exhaust is throaty, and generates a sympathetic resonant boom inside the cabin from behind at 2,700 to 2,800 rpm. All of this makes the provision of the very elaborate and no doubt expensive Delco-Bose radio/cassette player superfluous.

Solid state instrumentation is comprehensive (here seen in test mode — hence ail the 8s). Speedometer (left) and revcounter (right) have mg readings. Small centre panel uses dual purpose displays for minor bar graph pseudo-analogue plus numerical displays for accurate wings. Small centre panel uses dual purpose dis readings each side of bar-graph fuel gauge.

Plastic body has good all-round vision apart from block caused by wide B-post.

Road behaviour              

The European Corvette has, as explained earlier, the stiffer sports pack “Z51” suspension, which amongst other things, endows the car with very little roll. Ally that to those obviously highly responsive short, stiff- walled, wide-tread tyres, plus very high-geared steering – there are just 2 1/2 turns lock to lock for a mean turning circle diameter of 39 1/2ft, where an XJ-S has 2.9 turns for a similar lock — and little compliance, and you have a less than relaxing car. The ride doesn’t help; it is board like, reminding one of the Morgan Plus 8 in the way the car will patter askew if driven along a cobbled road. Even on good motorway, the ride is harsh enough to blur the interior mirror.

On first driving this Chevrolet, one finds it too twitchy even when running straight; it responds very rapidly to small steering wheel movements. Side winds seem to deflect it noticeably, and there is a distinct suggestion of tramlining effects from the tyres, so that on a long run it is far from being a comfortable car to drive. Fast running down a clear but uneven British country lane is close to frightening, because the stiffness of the springing makes one move up and down too much in the seat, which tends to induce unintended movements of the steering wheel — to which, as said already, response is very rapid. We cannot recall a road car, let alone an American one, where we have wished for lower- geared steering.

If you are feeling enthusiastic and right on the ball, and the road is not bumpy, the Corvette’s ultra-responsivenese is exciting and entertaining. It certainly has tremendous smooth road grip, as it should do with such tyres, and the quickness of the steering was valued during our return journey from Germany to Brussels, when the car abruptly slid crooked on a snowy autobahn; correcting the slide was ideally easy. It might not be so easy at high speed, when say a suddenly- encountered slippery patch or a bump on an otherwise good surface upsets any car. Catching a big car with such rapid steering and so little roll requires plenty of practice in private, wide space. It can be provoked into a tidy rear slide by decelerating sharply, then re-applying power — however, if the slide is too large, the lade of lock makes the Corvette almost impossible to correct. The steering does have some feedback, road bumps being felt at the wheel rim, and it self-centres well.

Brakes are similarly responsive and somewhat unprogressively, with the reaction to the same increase in brake pedal pressure rising as one nears the excellent 1g maximum stop at just 40lb effort. Even locking the front wheels — they go first — returns 0.98g, which is better than many other cars’ maximum stop. The Corvette didn’t really like our deliberately severe performance-related fade test, its brakes smoking badly on only the fourth V*g stop from a quarter-mile of acceleration, roughening badly thereafter, and ending up with a final tenth stop at over twice the initial pedal effort with the discs red and the pads on fire. To be fair, its brakes recovered quickly enough, and because they are so powerfully servoed, the final test stop required a shove on the pedal still well within anyone’s capabilities; other cars made in Europe have similar problems in fade resistance. The handbrake is not terribly effective, but will just hold the car on a 1 in 4 slope.

Behind the wheel

The view from behind the steering wheel is impressive, with the handsome uncluttered curve of the bonnet and its central bulge, a subtle suggestion of wheelarches, and at night the headlamps just projecting beyond. Closer to one sits the glowing solid-state instrument panel, its revcounter display an analogue of a power curve, the most unusually near- accurate speedometer which is another analogue (although both are in fact bar-graph type), with digital readings for specific indication. The small centre panel between revcounter and speedo includes digital readings as selected for oil pressure or temperature, range or trip mileage, coolant temperature or battery voltage, and instantaneous or average fuel consumption. The bar graph fuel gauge is vertically arranged in the middle. This central display is grandly if not inaccurately labelled “Driver Information Center”; it can be switched off if the driver wishes to minimise distraction, although along with the entire display apart from the radio’s clock, it does not dim when one switches on the lamps. To be fair, the display is not too bright, even at night. Overall, the instrument styling and design is excellent, with honest plain workings and lettering devoid of silly vulgarities.

The steering wheel can be altered over a small range both telescopically and in tilt. The driver’s seat is power-moved in height and fore and aft; seat back rake is manual, and a little limited for those who are both tall and long-armed, and who like to recline excessively. The range of movement aft is also surprisingly limited by the rear mini-bulkhead; there is enough leg room for 6ft testers, but taller types might not be ideally comfortable.

After European cars, for which steering column stalk switches for wipe-wash are near universal, the Corvette seems old-fashioned in one way, with its door-placed wiper and screen wash controls — not unhandy, but you do have to take a hand off the wheel. The clap- hands wiper blades tend to fight each other; they also tend to lift from 90 mph upwards, or at lower speeds when there is much wind. Unusually, they slow when washing, to avoid throwing too much water uselessly outwards. They also park very neatly, beneath the base of the screen. Vision out of the Chevrolet is not superlative. To the front one cannot complain, but the thick roll-over hoop B-post obstructs rearward side view.

The air-conditioning-cum- heating system is relatively sophisticated, controlling temperature well and responding adequately.

Living with the Corvette С4

The big doors could do with appreciably stronger keeps, so that they better resist unintentional shutting. On the other hand, some minor controls like the headlamp dip and windscreen wash are stiffer to work than usual. The electric windows are slow, taking nearly 5sec to lift, which is weak even by European standards, let alone American ones.

Central locking is fitted, but is mostly designed for use from within; the key only unlocks one door. The horn is worked ideally, from the middle of the steering wheel, where it can always be found quickly in any emergency. The interior map light has a courtesy delay switch-off.

Luggage space is comparatively generous considering the naturally body- space intruding design of the suspension in a low car, but 1 although there are compartments under the “boot” floor, the floor itself is quite high. It holds a surprising amount of luggage however, and what yon are carrying can be kept from prying sight by pulling over a roller blind. The Goodyear SpaceSaver spare is hung under the tail.

TESTERS SHORT LIST

Chevrolet Corvette (Automatic) £28,757 142 mph; 0-60 mph 6.6sec; 16.7 mpg                 

Jaguar XJ-S HE (Automatic) £21,752 153 mph; 0-60 mph 6.5sec; 16.0 mpg

Aston Martin V8 (Automatic) £42.498 146 mph; 0-60 6.6sec; 14.0 mpg  

Lotus Turbo Esprit £19,490 148 mph; 0-60 mph 6.1 sec; 18.0 mpg

BMW 635CSi (Automatic) £24,995 135mph; 0-60mph 7.6sec; 19.7mpg

Exact comparison cars to match the Corvette in its size and engineering are not plentiful, if only because even sporting cars with engines of over 5 litres are a diminishing (if happily not dead) breed. The price of the Chevrolet in Europe is, from its point of view, unfortunately inflated by the proverbial strength of the dollar, which at the British equivalent of its total Belgian price (including 33 per cent tax) costs nearly £29,000. In its native land, it is a very different story. The automatic Corvette costs around the same number of dollars, against 35,500 of the same currency for an XJ-S, 44.0 for a 928S and nearly 60.0       for a Ferrari 308. A further complication in comparison choosing for this particular test is that the subject is presently only available in Europe with automatic transmission, which is not to be found on the Quattro, either of the two Ferraris, both Lamborghinis, the Esprit Turbo or the Celica Supra. It can of course be argued that several of the cars we have listed if not short-listed are only very distant competition here; this applies especially to the otherwise excellent Capri (again manual only), which is mentioned solely because it is unrivalled in its very remarkable performance value for money.

The Corvette is very much a strict two-seater, where the Aston Martin, Audi, BMW, Ford, Jaguar, Mercedes, Nissan (soon to be replaced by the 300ZX), Opel, Porsche, Reliant and Toyota are all at least 2+2. It is a more practical two-some than its mid-engined rivals from Lotus and Ferrari, thanks to a pretty useful rear end; anyone considering buying the Chevrolet must however check the car carefully for comfortable legroom if he is above-average tall (over 6ft) — it is not nearly as generous in this respect as one might expect, given its size. The big American heed make no apology as far as its instrumentation and the amount of information it provides for the driver. Apart from its fuel gauge, which is not easily read at all times, it is highly comprehensive, the display is generally well designed, and happily devoid of the styling excesses one might fear from the wide possibilities offered by solid state technology. It also has one outstanding advantage over all its rivals, if one may go by this car and another tried earlier — its speedometer is very close to accurate.

Verdict

Shortlisting five rivals is, for the reasons explained, a matter of including two cars, the BMW and the Lotus, which are not such obvious candidates — especially the Lotus. It is of course the Esprit’s combination of one of the finest turbocharging installations so far (which gives it highly comparable performance and efficiency) with such superb roadholding, handling and ride that makes it a car that cannot be ignored, even in this sometimes exalted company; however, it is only obtainable in manual gearbox form. An Autotest of the latest 928S, is imminent; the old car with less power but manual transmission recorded 152 mph, 6.7 sec to 60,  and 17.5sec, It is obviously a strong contender, with fine slightly wary, ultimate handling, but the old ear suffered from an unfortunate marriage of high road noise and a body whose inside seems to amplify it.

The Jaguar is paramount if one wants a combination of fine automatic performance reliable handling, excellent ride and unrivalled refinement. It is also, considering its engineering quality, still good value, and has to be our favourite overall. Its only notable demerits are the vision over the shoulder, and economy that although better in HE form, is not a strong point — assuming that this matters to buyers in this field. The Aston Martin does much the same thing with overstatement; it is not quiet, but it is very entertaining in a brute sort of way. Where does this leave the Corvette? In ride, at the bottom of the class, by a long way, and also in refinement. It is also not the easiest car to drive really fast over a winding, bumpy road — but it is immense fun. It doesn’t shine as a long-distance runner, as a good Grand Tourer should — but drive it quickly over a give-and-take road for an hour, and you know you are living. We loved it, naughty as it is, and would certainly give it house room in our collection of contemporary classics.