GM North America’s FWD Platform Proliferation of the 1980s – A Guide To All 15 Platform Codes

(first posted 7/11/2017)      General Motors invested heavily in downsizing its lineup during the second half of the 1970s. With CAFE targets to meet and the potential threat of another oil crisis, the corporation saw its future inextricably entwined with smaller, front-wheel-drive vehicles. The industrial juggernaut undertook an ambitious plan to transform its lineup to FWD, starting the 1980s with two FWD platforms in the North American market and ending the decade with 15 separate FWD platform codes. Let’s decipher GM’s sprawling FWD lineup.

To make sense of it all, let’s go in descending order of size and positioning.


Launched: 1979

Sold as: Buick Riviera; Cadillac Eldorado; Oldsmobile Toronado, Buick Reatta

Wheelbase: 114 inches (1979-85); 108 inches (1986-93); 98.5 (Reatta, 1988-91)

The first front-wheel-drive E-Body, launched in 1966 as the Oldsmobile Toronado, was GM’s first front-wheel-drive platform. The Toronado was joined by the Cadillac Eldorado in 1967; Buick’s Riviera also shared the E-Body designation despite being rear-wheel-drive. This was an early example of GM’s confusing platform designations, where cars could switch designations, use a different one despite being mechanically identical, or use the same one despite being mechanically dissimilar.

The E-Body was downsized in 1979 for its third generation and the Riviera belatedly switched to front-wheel-drive like the others. All three ’79 E-Bodies used a 114-inch wheelbase, perimeter frame and four-wheel independent suspension with transverse torsion bars up front and semi-trailing arms, coil springs, and an anti-roll bar at the back. The Toronado and Eldorado were massively lighter than their predecessors by upwards of 1000 pounds and lost 12 inches in wheelbase length.

A further downsizing occurred in 1986 when the E-Bodies lost around 15 inches in total length, around 400 pounds in curb weight, and a lot of buyers. The downsizing was much less radical than the ’79 downsizing and yet undistinguished styling made it seem all the more shocking. Wheelbase was down by 6 inches to a total span of 108 inches and V8s disappeared from the Riviera and Toronado lineups, while convertibles disappeared entirely. Suspension was four-wheel independent once again, although the E-Body now used unibody construction instead of body-on-frame. Coil springs were used up front, MacPherson struts were used front and rear, while a transverse leaf spring spanned the rear (à la the Corvette).

Even after the ’86 redesign, the E-Bodies were still notably larger than the N-Bodies they were often derisively compared to. However, the more compact dimensions and appearance yet premium price pushed the once prestigious E-Bodies towards a fleet of similarly-sized vehicles including the perennial RWD G-Bodies. After a couple of years of disastrous sales, Cadillac launched a revised Eldorado that looked bigger; Buick and Oldsmobile followed in 1989 and 1990.

The Buick Reatta was also considered an E-Body despite a shorter, 98.5-inch wheelbase and only two seats. The basic chassis was carried over, however, as was the Riviera’s powertrain and dashboard.


Launched: 1980

Sold as: Cadillac Seville

Wheelbase: 114 inches (1980-85); 108 inches (1986-93)

GM continued the K-Body platform code of the first Seville despite the move to front-wheel-drive. The first K-Body had been a revised RWD X-Body, while the second K-Body was identical to the E-Body and shared its 114-inch wheelbase. The Seville’s engines were the same as the Eldorado’s, a veritable grab-bag of GM’s worst powertrains: the flaky V8-6-4; the disastrous 5.7 Oldsmobile diesel; and the weak HT-4100 V8.

When the E-Body Eldorado was revised in 1986, the Seville followed suit and continued to share a platform with the Eldorado. Again, engines were the same. Well, “engine”. The diesels were gone and the old credit-option Buick 4.1 V6 was no more, leaving just the HT-4100 (later replaced by 4.5 and 4.9 V8s). GM continued to call the third-generation Seville a “K-Body”.


Launched: 1987

Sold as: Cadillac Allanté

Wheelbase: 99.4 inches

The Allanté, like the Buick Reatta, used a shortened version of the E-Body floorpan. However, the Allanté’s wheelbase was slightly longer than the Reatta at 99.4 inches and it received its own platform designation.

As Cadillac’s flagship, the Allanté was given some exclusive hardware to justify its hefty price premium. A specially-tuned, multi-port fuel-injected version of Cadillac’s HT-4100 was the only engine available in the Allanté at first, producing 40 more horsepower and 35 more pound-feet of torque than the regular HT-4100 for a total of 170 hp and 235 ft-lbs. From 1989, the two-seater Cadillac offered a computer-controlled suspension system with adjustable dampers.

The Allanté hung in there for a few years despite disappointing sales. However, its unique selling points were sacrificed along the way—from 1989, it used the same 4.5 V8 as in other Caddys and the computer-controlled suspension was introduced to the Eldorado line in 1991. The Allanté was one of the first Caddys to use the Northstar V8, introduced in what would prove to be the roadster’s final year.


Launched: 1985

Sold as: Cadillac DeVille, Cadillac Fleetwood, Buick Electra, Oldsmobile Ninety-Eight

Wheelbase: 110.8 inches (all except 1989-92 Cadillac DeVille/Fleetwood sedan); 113.8 inches (1989-92 Cadillac sedans)

The full-size C-Body platform commenced development in 1980 in the aftermath of a second oil crisis and soaring gas prices. The C-Body cars were around two feet shorter than their predecessors, around 600 pounds lighter, and now used unit-body construction with a separate front subframe. Suspension was now fully independent with MacPherson struts and stabilizer bars front and rear, and electronic level control at the rear.

GM’s sweeping redesign of the C-Body was a risky gambit for a platform that was popular with older, more conservative buyers. The Cadillac, in particular, was a dramatic change from its predecessor, although it was the only C-Body to retain V8 power. That carryover HT-4100 made the new FWD DeVille and Fleetwood much more sprightly – relatively speaking, that is – than the RWD models which continued to be sold alongside. Although sales remained steady, GM still ordered an extensive mid-cycle enhancement for the DeVille in 1989 that stretched the sedan’s wheelbase by three inches.

Tastes had changed by the 1980s and coupes were falling out of favor. The C-Body coupes in particular haemorrhaged sales. However, each of the C-Body lines continued to sell in the same overall volume in the second half of the 1980s as their RWD predecessors had in the first half, making this one of GM’s more successful downsizings.


Launched: 1986

Sold as: Buick LeSabre, Oldsmobile Delta 88, Pontiac Bonneville

Wheelbase: 110.8 inches

The H-Body was introduced one year after the launch of the FWD C-Body. The platform code had previously been used on a completely unrelated RWD subcompact platform, used by the Chevrolet Monza and axed after 1980. The new FWD H-Body shared the more modern unit-body construction and suspension set-up of the C-Body with no major mechanical differences. The C and H-Bodies were instead distinguished from each other visually—the H cars employed a more rakish roofline that was a pleasant change from GM’s obsession with formal rooflines in the 1980s.

Although buyers of LeSabres were typically older, more conservative buyers, the downsized H-Body LeSabre continued to sell quite well, as did the Bonneville. This was despite the trimmer dimensions and the lack of a V8. The FWD Delta 88 saw sales dip, but this was unfortunately a pervasive problem in the ‘80s at Oldsmobile.

W-Body (GM-10)

Launched: 1988

Sold as: Buick Regal, Chevrolet Lumina, Oldsmobile Cutlass Supreme, Pontiac Grand Prix

Wheelbase: 107.5 inches

The first W-Body sedans didn’t arrive until MY1990 – two years after the coupes – and this was one of the main reasons the W-Body’s launch was so bungled and disappointing for GM. Three of these models carried over nameplates from RWD G-Body cars, meaning these were GM’s second attempt to replace that perennially popular Regal, Cutlass Supreme, and Grand Prix.

As covered in greater detail earlier, the W-Body’s development was plagued with delays, huge production costs, and all-round mismanagement. When they finally arrived, they didn’t represent a quantum leap forward for GM and this was reflected in the mostly unenthusiastic press coverage. More troubling for GM, buyers were also apathetic.

Early models used the carryover Chevrolet 2.8 V6, while the four-wheel independent suspension was quite similar to the existing E-Body, down to the transverse leaf spring (it’s unclear whether there was any parts commonality). That was more modern than the set-up in the A-Body these cars sort of replaced and by most accounts these cars rode and handled better, if not quite as well as the Taurus. But the GM-10 cars also weighed upwards of 500 pounds more than the A-Body, which meant GM had to introduce stronger engines after a couple of years simply to keep them as quick off the line as the outgoing 2.8 A-Bodies. Also, despite riding a 1.5-inch longer wheelbase than the Taurus, the interior was no more spacious.

Although the Grand Prix and Lumina effectively replaced the A-Body Pontiac 6000 and Chevrolet Celebrity, respectively, the Regal and Cutlass Supreme continued to be sold alongside their A-Body Century and Cutlass Ciera predecessors. But let’s save the tangled web of FWD GM platforms in the ‘90s for another time.


Launched: 1982

Sold as: Buick Century, Chevrolet Celebrity, Oldsmobile Cutlass Ciera, Pontiac 6000

Wheelbase: 104.9 inches

The A-Body got off to a slow start, sales-wise, but quickly turned out to be perhaps the most successful of GM’s new front-wheel-drive platforms. Contrast that with the GM X-Body of 1980, enormously successful out of the gate but collapsing once its reliability problems became known. GM had worked out most of those reliability issues by 1982, which was fortunate as the A-Body was simply an X-Body with a longer, more formal body.

That extra length was not found in the wheelbase but, rather, in the overhangs. This allowed for a larger trunk and a larger engine compartment, which in turn lead to the introduction of larger engines like Oldsmobile’s 4.3 V6 diesel (available in all four lines) and Buick’s 3.8 V6 (available in the Olds and Buick).

The A-Body platform proved to have a lot of life in it. It was used as the basis for the U-Body minivans of 1990, and the Century and Cutlass Ciera were sold all the way until 1996 by which time the diesels, coupes, 6000s and Celebrities were long gone.


Launched: 1980

Sold as: Buick Skylark, Chevrolet Citation, Oldsmobile Omega, Pontiac Phoenix

Wheelbase: 104.9 inches

Development of the FWD X-Body started in 1974. Although this coincided with the fuel crisis, GM had been planning since 1972 on developing a smaller, more efficient replacement for the RWD Chevy Nova (and its X-Body cousins). This new Nova would be sized similarly to the German Opel Rekord. The fuel crisis did shake up GM’s product plans, however: they decided to downsize their entire lineup, and also opted to make the Nova replacement just a smidgeon smaller. The FWD X-Cars ended up being sized almost identically to the Rekord, with a difference of just a couple of inches in most dimensions. How funny: GM “downsizes” their compact models and they still end up being equivalent in size to a full-size car in Europe.

GM designers did their best to make the new X-Body Buick Skylark and Oldsmobile Omega look like their bigger RWD siblings, offering them only as two- and four-door notchbacks, while the Chevrolet Citation and Pontiac Phoenix received a two-door notchback but also a clean, almost European hatchback design. Although the new X-Cars were six inches shorter in wheelbase, their cabins were more accommodating and space-efficient than that of their predecessors. V8 engines were gone – replaced with four- and six-cylinder engines – but the new cars’ sizeable weight savings (over 500 pounds) meant performance was just as good.

These were GM’s first non-luxury FWD cars and set the blueprint for many of GM’s FWD platforms in the 1980s. Suspension up front consisted of McPherson struts with lower a-arms and an anti-roll bar; out back was a beam axle with an integral anti-roll bar, trailing arms, and a Panhard rod. Coil springs and tube shocks were featured front and rear. It wasn’t as cutting edge as some of the imports but these were sized right, looked good and were destined for success.

If only GM had paid more attention to quality and reliability. Sales of the Citation cratered once consumers learned of the many recalls and issues, while the Omega and Phoenix were never particularly popular. Only the Skylark stayed steady. Once the J-Body and A-Body arrived in 1982, the X-Cars were awkwardly situated in their division lineups—although the J-Cars were a couple of inches shorter in most dimensions, they were priced virtually identically to the X-Cars. Only the Citation – renamed Citation II – and Skylark survived until 1985, with the slow-selling Omega and Phoenix axed after 1984.

N-Body (GM20)

Launched: 1985

Sold as: Buick Somerset/Somerset Regal/Skylark, Oldsmobile Calais/Cutlass Calais, Pontiac Grand Am

Wheelbase: 103.4 inches

The X-Body was replaced, somewhat indirectly, by the slightly smaller N-Body and related L-Body. As their original names suggest – Somerset Regal, Calais, Grand Am, all formerly used by the RWD A-Body – these were designed to replace the RWD G-Bodies and development began in 1980. GM’s dire predictions of a future of high gas prices proved to be off-base, leaving the RWD G-Bodies to sweep up sale after sale long after GM had intended to euthanize them. That left the N-Body cars to slot into the B-O-P model ranges as premium compacts, filling the space between the “subcompact” J and mid-size A cars and therefore serving as de facto replacements for the X-Cars.

Although these were nominally larger than the J cars, underneath they were much the same. This meant the same suspension set-up: MacPherson strut suspension up front and a twist-beam axle out back with trailing arms. There was hope that these would be effective competition for the hordes of sporty compacts from Japan and Germany, but they turned out to be little more than J-Cars in fancier duds. Buyers had a choice between the uninspiring Tech IV 2.5 four or the Buick 3.0 V6. Sadly, the latter was not available with a manual transmission. In 1986, sedans joined the N-Cars lineups while Oldsmobile’s modern (if thrashy) Quad 4 became available in the Calais in 1987 and later on the other N-Cars. A turbocharged 2.0 four was also available briefly in the Grand Am. Of the three cars, the Grand Am was the strongest seller; it was also the only one that had a consistent name, as the Somerset Regal coupe became Somerset in 1986 and then was renamed Skylark like its sedan counterpart in 1988, and the Calais became Cutlass Calais for 1988.


Launched: 1987

Sold as: Chevrolet Beretta, Chevrolet Corsica, Pontiac Tempest (Canada only)

Wheelbase: 103.4 inches

It’s not clear if there were any major differences between Chevrolet’s L-Body and the B-O-P N-Body. Both platforms used the J-Body’s suspension set-up and while some sources report the L-Body used a mixture of J- and N-Body components, those two platforms already shared a lot. The J-Body’s MacPherson strut front suspension was retained, as was the twist-beam axle at the rear.

Interestingly, Pontiac of Canada received a rebadged Corsica badged Tempest despite the presence of the Grand Am in their showrooms. Pontiac’s popularity up north had also seen the arrowhead badge applied to the Suzuki Swift (Pontiac Firefly) and Suzuki Sidekick (Pontiac Sunrunner).


Launched: 1982

Sold as: Buick Skyhawk, Cadillac Cimarron, Chevrolet Cavalier, Oldsmobile Firenza, Pontiac J2000/2000/2000 Sunbird/Sunbird

Wheelbase: 101.2 inches

Much like the 1973 T-Car platform used by the Holden Gemini, Chevrolet Chevette and Opel Kadett, among many others, the J-Car was designed as a global platform. When development commenced in the mid-1970s, the plan was for the J-Car to be sold by Holden in Australia, Isuzu in Japan, and Opel and Vauxhall in Europe. In 1977, GM North America decided to join the project, which by now was pooling talent and resources of GM engineers from around the world.

Cadillac had very little to do with the development, having joined the project just 11 months prior to the J-Cars’ arrival in showrooms in 1981—this explains why the Cimarron ended up being little more than a Cavalier with nicer trim.

The suspension set-up was largely similar to the X-Body’s, with MacPherson struts and coil springs and an anti-roll bar up front and coil springs, trailing arms and interconnecting torsion beam at the back.

As with many “world cars” that wind up in the US, the North American J-Cars ended up being considerably different from their cousins in Europe and the Asia-Pacific region. Instead of using the Family II four-cylinder engine like the global J-Cars, GMNA fashioned a 1.8 four-cylinder from the 90-degree V6 engine.

Although the J-Cars used a new unibody, to keep costs down GMNA cribbed the larger X-Body’s front suspension, steering system, CV joints, wheel bearings, starter motor, transmissions and various other parts. As these parts were beefier, intended for use on a vehicle 400-500 pounds heavier, the American J-Body ended up overweight for its class—a base Cavalier weighed in around 300-400 pounds heavier than the target Accord. This stifled performance, already underwhelming from the wheezy 1.8, and lead to the introduction of more powerful four-cylinder engines (including the Family II, albeit only in the J2000) and even Chevy’s 2.8 V6. Still, GMNA got plenty of mileage out of this platform and after a rocky start, sales of the Cavalier and J2000 (later Sunbird) soared; the Buick, Olds and Cadillac versions wouldn’t survive into the new decade, however.


Launched: 1988

Sold as: Pontiac LeMans

Wheelbase: 99.2 inches

While GMNA continued to foist the hoary, outdated Chevrolet Chevette and Pontiac T1000 on American and Canadian buyers, GM of Europe moved on and developed a front-wheel-drive replacement, the Opel Kadett D and Vauxhall Astra, which launched in 1979. By the time the Chevette and T1000 were finally being euthanized, the Kadett D had been replaced by the Kadett E (launched in 1984). North American consumers eventually received it in 1988, and it was keenly priced.

Suspension set-up wasn’t anything too unfamiliar for North American buyers: MacPherson struts up front and coil springs, trailing arms, and a semi-independent torsion beam out back. The modern, overhead cam Family II engine was available in either 1.6 or 2.0 displacements. Sadly, the Pontiac LeMans was manufactured by Daewoo of Korea and, although it looked the same as the Astra from which it was derived, the driving excitement had been sucked out of it and the build quality was no better than that of a Hyundai Excel.

The LeMans continued as Pontiac’s bottom-feeder price-leader until 1993 when it was axed, although it continued to be manufactured in South Korea, Egypt, and Uzbekistan for many years thereafter.


Launched: 1985

Sold as: Chevrolet Spectrum, Geo Spectrum, Isuzu I-Mark, Pontiac Sunburst (Canada)

Wheelbase: 94.5 inches

Although Isuzu and Opel had both participated in the global RWD T-Car project, GM’s European arm and Japanese partner went their separate ways. Isuzu (as well as Holden) continued with the honest RWD T-Car into the mid-1980s, known in most markets as Gemini. The subcompact and compact segments had rapidly shifted to majority FWD so for 1985 the Gemini would move to a new FWD platform. This new Isuzu would be sold not only as an Isuzu I-Mark in North America, but also as a captive import in Chevrolet showrooms.

The Spectrum was priced between the Suzuki-sourced Sprint and Toyota-sourced Nova. Confusingly, Chevrolet sold numerous subcompacts and compacts alongside each other in a cluttered lineup. The antediluvian Chevette opened the Chevy lineup, undercutting the smaller Sprint. The Spectrum was priced above the Sprint and right at the low-end of the larger Cavalier’s price range, while the Nova was priced slightly above the Spectrum but below top-spec Cavaliers. The Spectrum range was trimmed for 1989, gaining a Geo badge in the process, but by 1990 it was gone.


Launched: 1984

Sold as: Chevrolet Sprint, Geo Metro, Pontiac Firefly (Canada), Suzuki Forsa (Hawaii, U.S. territories), Suzuki Swift

Wheelbase: 88.4 inches/92.3 inches (Sprint 3-dr/5-dr), 89.2 inches/93.2 inches (Metro 3-dr/5-dr)

The first Suzuki Cultus/Swift was born from the ashes of GM’s aborted M-Car project. GM had realized during development that production costs would have been too high to ensure profitability and sold the blueprints to Suzuki in exchange for a 5% share in the Japanese automaker. Another term of the agreement was GM would have access to the Swift as a captive import in North America, Australia, and other global markets.

This agreement continued with the Swift’s successor, and by then GMNA was selling captive imports under the Geo banner. In a market generally bereft of true subcompacts, the Metro ended up becoming one of the most well-known small cars because of its size, maneuverability, and terrific fuel economy. Although the second-generation Swift had no GM involvement in its design, the corporation continued to refer to the car internally as being an M-Body.


Launched: 1986

Sold as: Chevrolet Nova, Geo Prizm

Wheelbase: 96 inches (Nova), 95.7 inches (first-gen Prizm)

It appears GM may have internally referred to the Chevrolet Nova (and its Geo Prizm successor) as the GM S-Body although GM had no involvement in the development of the fifth-generation Toyota Corolla that spawned it. However, the corporation partnered with Toyota on a joint venture – New United Motor Manufacturing Inc. – to manufacture it and a rebadged derivative, dusting off the Chevrolet Nova nameplate. The aim of NUMMI was to learn about lean manufacturing, a practice widespread among the Japanese automakers. With four-wheel independent suspension (MacPherson struts all round), overhead cam four-cylinder engine, and impressive levels of fit and finish, the Nova and Prizm were rather different from other small cars bearing the Chevrolet badge.

There we have it: all 15 of GM’s FWD platform codes in the 1980s, a tangled web of interrelated platforms (J, N, X, L), platforms with different names for no reason (K, H), and platform codes given to products not even developed by GM (S).

With the rise of modular platforms and greater manufacturing flexibility, GM now uses just five separate platforms for its front-wheel-drive vehicles in North America (six if you count the moribund Delta platform underpinning the Buick Cascada and Verano). Those platforms are Gamma, D2XX, E2XX, Epsilon II, and C1XX.

That’s much more simple.

Related Reading:

Jason Shafer’s seminal Curbside Classic Comprehensive Chronology of the Chrysler K-Car Family Tree