The GM H platform is a 2-door notchback coupe / 2-door fastback coupe / 3-door hatchback / 3- door wagon / 3- door panel delivery from GM (General Motors). Under the bonnet: 140 CID 2.3 Liter OHC 1bbl I4.
Where it came from
The General Motors H platform (or H-body) is an automobile platform used by subcompact cars from the 1971 to 1980 model years. The first subcompact car design developed by GM, the rear-wheel drive H platform initially underpinned the Chevrolet Vega and its Pontiac Astre counterpart. For 1975, the H platform was expanded from entry-level vehicles to sport compacts, adding the Chevrolet Monza, Buick Skyhawk, Oldsmobile Starfire, and Pontiac Sunbird. In contrast to the globally-developed T platform (later sold alongside it), the H-platform was sold nearly exclusively in North America.
Following the downsizing of its larger car lines (the B-body full-size, A-body intermediate, E-body personal luxury), GM moved to redesign the rest of its major model lines. Following the 1980 shift of the X-body compacts to front-wheel drive, the H platform ended production for the 1980 model year. For 1982, the H-body vehicles were replaced by the front-wheel drive J-body; while again shrinking in length, the interiors of the J-body vehicles grew in size, becoming compact-segment vehicles. From 1986 to 1999, the H platform designation was revived for front-wheel drive full-size sedans of the Buick, Oldsmobile, and Pontiac divisions.
Under the skin
Power comes from 140 CID 2.3 Liter OHC 1bbl I4; other versions carried different engines, listed in the specification table below. It shifts through a 3-speed manual / 4-speed manual / 5-speed manual w/overdrive / Torque-Drive clutchless manual / Powerglide 2 spd. automatic / Turbo-Hydramatic 3 spd.automatic. The layout matters: a front engine drives the rear wheels, the classic proportion — long bonnet, cabin set back — that most people picture when they picture a sports saloon or a grand tourer. The wheelbase is 97.0 in. These are manufacturer figures carried by Wikipedia and Wikidata, not road-test measurements.
In context
Its family tree is legible: its successor was the General Motors J platform; assembly was at Lordstown, Ohio. Nearby in the GM (General Motors) catalogue sit the 1955 Chevrolet and the 1957 Chevrolet.