The third generation Corvette – from 1968 to 1982 is patterned after the Mako Shark 11 concept car. For the first time the car is offered with a removable “T” roof. He body and interior were changed in the C2 cars although most of the power train components are the same. A 350 cu in (5.7 L) replaced the 327 as basic equipment but horse power rating stayed the same. The optional big block engine;” ZL1” was all new and all aluminum; it was listed at 430 BHP (320 kW) but reportedly was as high as 560 BHP (420 kW) and would do the quarter mile in 10.89 seconds. In 1970 the small block engine option was the high compression, high revving “LT-1” producing 370 BHP (276 kW). The big block option was the 454 cu in (7.44 L) producing 390 BHP (291 kW). From 1970 through 1972 the “ZR-1” racing equipped engine was available – there were only 53 of these built.
New emission regulations came into effect in 1971 and all the ‘vette engines had horse power ratings reduced by about 10% to conform and accommodate the new non-leaded fuels. The exception was the 350 cu in and the horse power remained the same but in 1972 the horse power rating system changed so rather than using “gross” ratings; “net horsepower” figure is used which dropped the ratings a further 25% or so but it is a more accurate figure. The 1975 models had the duel exhaust system left over from the ’74 model year but with a catalytic converted added which made the use of unleaded fuel mandatory to avoid burning out the converter. The floor was changed from fiberglass to metal as protection from the heat of the converter. The horse power rating began rising on succeeding models and peaked in the 1980 model year. The styling changed was slight until the 25th anniversary edition in 1978 although the “Stingray” moniker was changed to one word from ’69 through to ’76.
In 1970 the interior was updated with new style seats and the car had fender flares added; the rear bumper stayed chrome but the front bumpers were changed to a polyurethane material to be in line with the 5 mph (8 km) crash test regulations. The 1973 ‘vette was the last model to have any chrome bumpers used – in the future both the front and rear would be polyurethane. The last year for the tunnel roof with vertical rear window and the last year for the convertible is 1974 and the top would not return for eleven years until an integral roll bar is designed. This is the first year the ‘vette could be ordered with leather seats.
The twenty-fifth anniversary of the ‘vette is 1978 and the car can be had in two tone silver over gray; this is the first year as well the car is used as a pace car in the Indianapolis 5oo. The ’78 ‘vette introduced the fast back rear window and also featured a new interior with a redesigned dash. The 1979 offered the pace car style seats as an option and also offered front and rear spoilers if you would like. The 1980 corvette becomes more aerodynamic and also became lighter as both the body and chassis had unneeded material removed. The standard transmission was offered for the last time in 1981 and would not be available again until late in 1984. For 1982 models fuel injection returned as an option. The last C 3 cars offered an opening rear window hatch as an option in 1983.