Chevrolet Impala Wagon
The Impala remained Chevrolet's top-selling model with the fifth generation. A high-performance big block V8 was still available in the form of the Turbo-Jet 454, which produced 365 hp in 1971, but power decreased as the years went along. The 1971 redesigned B-body would be the largest car ever offered by Chevrolet. The hardtop Sport Coupe continued to be offered; it was a smoothly sloped semi-fastback reminiscent of the 1961 "bubbletop" styling. A three-speed manual transmission remained standard at the beginning of the year, but in the spring of 1971 all V8-equipped full-size GM cars got Turbo Hydra-Matic as standard equipment. Interestingly, Power-glide remained optionally available for six-cylinder cars until the 1973 models.
The 1972 model introduced a grille which extended below the bumper. Powertrains consisted of mostly V8 engines. The 250 inline six was still standard for Sport Coupe and 4-door sedan models; the 350 2bbl V8 became the standard engine from 1973–1976, with 350 cubic inches (5.7 L), 400 cubic inches (6.6 L), 402 cubic inches (6.6 L) (through 72) or 454 cubic inches (7.4 L). The best-selling body style was the Custom Coupe. Beginning in 1972, all engines were designed to run on unleaded gasoline. 1972 saw the last Impala convertible; it sold 6,456 copies, placing fourth with just under 9 percent of the market, right behind the Corvette 6,508, ahead of the Mustang's 6,401.
1973 Chevrolets featured a larger, shock-absorbing front bumper due to new federal mandates which required 5-mile-per-hour (8.0 km/h) impact protection. New taillights were mounted in the (still) conventional rear bumper. This was the first year of the Caprice Classic convertible. Tweaks to the suspension and frame gave better roadability, according to Chevrolet general manager John Z. DeLorean. Steering wheels and instrument panels were color-keyed to interior colors, as opposed to the matte black used in 1971–72. The inline six-cylinder engine was now offered on the Bel Air 4-door sedan only, and only with the 3-speed manual transmission.
In 1974, the rear bumper was redesigned with shock absorbers to meet the upgraded standards and new tail lights were featured. The front end was also freshened as in previous years, with a new grille and headlight bezels, a new header panel, and a bumper with a drop down center section. The marker lights moved back up beside the headlamps once again. This was the only year of the 1971–1976 models the Impala had a different front end design than the Caprice Classic, as other years used either a grille insert or previous year Caprice front to distinguish the two. The rooflines of the Impala coupes were also revised. For 1974 the Custom Coupe was no longer a hardtop, with large fixed rear quarter glass and a thick B-pillar. The Sport Coupe, still a pillar-less hardtop, now used larger roll-down quarter glass like that of the 1971–73 Custom Coupe, and had a narrower, fastback style, flat back window. Sedans used carryover body shells from previous years.
Source: Wikipedia, 2012