Production of the C3-series models ceased towards the end of 1982, and a brief gap ensued until the launch of the 1984 model-year versions at the end of '83. These C4-series 'Vettes maintained the same basic recipe, but had been thoroughly overhauled under the surface, with a little help from GM-owned Lotus, who had tuned and developed the suspension system in an attempt to give the car a more European feel. Corvette C4 was nearly 25 percent more aerodynamic than its predecessor, with a drag cooefficient of 0.34, but this barely compensated for its weight gain - it was now over 1400kg, despite all the lightweight components and its shorter, lower body. Wider than before, it was built on a new type of 'birdcage' uniframe construction of galvanised steel, with a one-piece removable roof panel, a lift-up rear window and a front-opening clamshell bonnet.
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Now with forged aluminium suspension arms, front double wishbones and an anti-roll bar, the handling of the C4 was benchmarked against cars like the Porsche 928 - large, heavy yet still agile super-GTs. The ride became much firmer, in part due to the fitting of much lower-profile tyres, and the steering much more precise, thanks to a low-ratio rack and pinion system. Under chief engineer Dave McClellan, new technologies such as ABS anti-lock brakes, traction control, keyless entry and airbags were introduced - making their debut in the Chevrolet line-up - and a motorsport programme reinstated, with many successes in endurance racing and the winning of all the races in the '85,'86 and '87 SCCA series. Critics of the C4 found the ride too harsh and refinement poor - even with the standard set-up, let alone the optional Z51 and Z53 performance systems - and disliked the slightly twitchy, over-sensitive steering, but on the whole, it was better-received in Europe, not least because a four-speed manual gearbox with overdrive was now available, as well as the four-speed auto slushbox. The manual was said to be hard going, however, with a truck-like action, and it was quietly dropped from the options list by 1988.
Minor changes ensued throughout the '80s, with the main advance being the addition of tuned-port fuel injection on the 230bhp 5.7-litre V8 engine (1985). A convertible model returned to the line-up in '86, and this was used as the Indy pace car. Sales were declining, however, and in 1988, fell to 15,382 coupes and 7,407 convertibles. The Corvette was also banned from the SCCA race series it had dominated, though Chevrolet launched its own championship, the Corvette Challenge. Into the '90s, and three-mode suspension was now offered (Touring, Sport and Competition settings), and a driver's airbag became standard equipment. Two-mode ignition was also offered: one key turned on the engine to just 80 percent of its power, with just three valves and one injector per cylinder active, and another, the 'valet key', to release the rest. "A precautionary measure," engineer McClelland told Car magazine. "There are owners who would prefer their spouses or sons not to be in command of the ZR-1's full performance potential."
1990 brought the launch of the ZR-1, too: this had an all-new 32-valve, 5.7-litre aluminium V8, producing 375bhp at 5800rpm (uprated to 405bhp in 1993). "America (with a little help from Lotus) builds a decent sports car at last," screamed the cover headline of Car (May 1989). Car slammed its bright, tacky cabin ("an ergonomic disaster"), cheap plastics and carpets, unreadable digital instruments, indifferent build quality, poor ride quality, unresponsive understeer-prone handling and the output-stifling American emissions regulations, but praised the six-speed manual gearbox (except in the high-set sixth gear, when need for economy overrode need for acceleration), the roadholding and straight-line acceleration. "The 3454lb Vette takes off like a rocket. Wheelspin in first and second gear is the easiest trick in the book. Traction is quite superb." Against the odds, writer Georg Kacher rather enjoyed it, and decided that it ran the Porsche 928 very close; "it is so much easier to drive fast", even if it was still the inferior car.
The sportier ZR-1 exterior became standard-fit on lesser-powered models as well, which gained the LT1 V8 in 300bhp in 1992, the year the millionth Corvette was made. Refreshed styling brought rectangular tallights, a more tapered nose and new front bumpers. Motorsport activity continued, with the Corvette allowed back into the SCCA series, and in 1994, a Callaway SuperNatural Corvette Le Mans, a special-bodied example with carbonfibre panels, won its class at the Le Mans 24 Hours; two Callaway cars were then second and third a year later. Sales of the production cars remained steady, though the ZR-1 was phased out in '95, and the racing successes ensured the interest of the Corvette faithful, if not the world's sports car cognoscenti.
