In the context of the automobile industry, downsizing is a practice used to transition vehicles from one size segment to another. Commenced during the Malaise era, downsizing is done in response to consumer and government demands influencing vehicle design. As vehicle product lines completed their model cycles, automobile manufacturers developed the next generation of a vehicle with a smaller exterior footprint to allow for weight reduction and increased fuel economy, using a shortened wheelbase and body length.
In the American automobile industry, downsizing was a direct response to the 1973 oil crisis, which resulted in the enaction of CAFE fuel economy standards in 1975. By 1980, each auto manufacturer producing cars and light trucks for sale in the United States were required to produce an average of 20 mpg across their entire product line. In response, as full-size car lines completed their model cycles, General Motors, Ford Motor Company, and Chrysler Corporation sought to introduce full-size product lines with increased fuel efficiency while preserving interior dimensions as closely as possible. In 1977, General Motors became the first American manufacturer to introduce downsized versions of its full-size product line.
By the early 1980s, the downsizing practice had expanded to nearly all size segments as product lines completed model cycles within each company. Outside of the full-size segment, American manufacturers began to align more closely with European and Japanese manufacturers in size segments, leading to the abandonment of the North American-specific "intermediate" size segment. As a quicker and lower-cost alternative to complete model redesigns, a second strategy transitioned nameplates of larger vehicles to smaller ones as part of model updates.
The term engine downsizing is used when a manufacturer introduces a smaller-displacement engine (though not necessarily lower-output) for a product line in the interest of higher fuel economy.
Research and progress
The University of Bath published research carried out by its Powertrain and Vehicle Research Centre which demonstrated that it is possible to reduce engine capacity by 60% and still achieve the torque curve of a modern, large-capacity naturally-aspirated engine, while encompassing the attributes necessary to employ such a concept in premium vehicles.
Examples
General Motors
From 1977 to 1982, in order, General Motors would physically downsize its full-size, intermediate, compact, and subcompact vehicle product lines as each platform completed its model cycle. The strategy included vehicles from every General Motors division (Buick, Cadillac, Chevrolet, GMC, Oldsmobile, and Pontiac).
Full-size (B/C-platform, 1977) As a direct response to the 1973 oil crisis, the first automobiles to undergo downsizing in the interest of increased fuel efficiency were the full-size GM B-body and C-body platforms (used by all divisions except GMC). Used by the Buick LeSabre/Electra, Chevrolet Impala/Caprice, Cadillacs, Oldsmobile 88/98, and Pontiac Catalina/Bonneville, the B and C-bodies were among the best-selling car platforms in North America at the time. On average, from 1976 to 1977, engineers shed an average of 12 inches of body length and 750-800 pounds in curb weight (with some vehicles losing over 1,000 pounds of curb weight).
For 1977 only, the full-size GM product line adopted a smaller exterior footprint than the A-platform intermediates; careful engineering led to negligible reductions of interior space over preceding full-size vehicles. In both the interest of fuel economy and weight reduction, the B/C-platform ended the use of "big-block" V8 engines outside of the Cadillac division; after 1980, a 350 cubic-inch V8 was the largest engine fitted in a B-body chassis.
In 1985, General Motors underwent a further downsizing of many of its nameplates using the B-platform chassis. With the exception of station wagons, the full-size cars of Buick, Oldsmobile, and Pontiac (along with most of the Cadillac model line) were downsized, becoming front-wheel drive, mid-size sedans. From 1986 to 1990, the sole rear-wheel-drive sedans produced were the Chevrolet Caprice and Cadillac (Fleetwood) Brougham; the Buick Roadmaster sedan was introduced for 1992.
Following the end of the 1996 model year, General Motors ended production of the B-platform. While not intended as a direct replacement, GM sourced sedans based from the GM Zeta platform from 2008 to 2017, produced by Holden (GM Australia).