General Motors uses letter codes to signify which chassis layout, or body type, the vehicle has. This is useful since GM consists of many different makes such as Chevrolet, Oldsmobile, Pontiac, Buick, and Cadillac. Many of these brands share platform types with each other. It isn’t some secret, alphabetic code that GM fans are privileged to. It is really quite simple. Each platform has changed somewhat over the years so we’ll walk through them in more or less chronological order.
The Early Years
GM started with just four platforms: the A, B, C, and D bodies. In the beginning, A and B were both for full size cars. A body models included the Chevy Superior, the Oldsmobile 60, and most Pontiacs. The B Body was used for the Buick Century among others. GM decided it didn’t make sense to have two platforms for full size cars so the A body was discontinued and the B Body became the standard for full sized cars in 1959. GM continued to use the B body designation for full size, rear-wheel drive cars until 1996. The Chevy Bel Air, Buick LeSabre, Chevy Impala, and Pontiac Bonneville were all built on the B body platform in this era.
In 1931, GM Introduced the C body. The C body would continue as a long wheelbase RWD car until 1984. The C body was essentially a lengthened version of the B body. The Pontiac Torpedo, Buick LaSalle, and Oldsmobile 90 were built on this platform.
In 1960, Chevy introduced a car that was different from anything else in GM’s lineup at the time. The Corvair was a rear-engined, compact car. Obviously, the chassis was quite different from other GM cars. So, from 1960-1969, the Corvair and its variants had their own platform as the Z-body.
In 1962, GM introduced another platform for compact cars, the X body. The X body was used for the Chevy II early on. Similarly to what happened with the A and B bodies, GM had duplicate platforms with the X and Y bodies. The Y body was phased out after only a couple years, in 1963. The X body would continue as GM’s main compact platform until 1979. The X body would be used for the Chevy Nova, 1970s Buick Skylarks, and the Pontiac Ventura.
The X body was followed by the E body, in 1963. The E body was used for Personal luxury cars like the Buick Riviera, Oldsmobile Toronado and Cadillac Eldorado. Strangely, some early E bodies, like the Tornado, were front wheel drive, and some, like the Riviera, were rear wheel drive. FWD E bodies were the first front wheel drive cars produced in the United States since 1937. By 1979, E bodies were all FWD. They continued in this configuration until 2002. This began GM’s slow shift toward focusing on FWD cars.
The A body, absent since 1959, made a return in 1964. GM decided to reuse the A body name for its midsize cars like the Chevy Chevelle, and the Pontiac Tempest. The A body continued as a RWD platform until 1981.
GM’s European subsidiary, Opel, developed another RWD platform, the V body in 1966. It was used for various European and Australian market products from 1966 until 2006. Some of these models were imported to the US in the late ‘90s and early 2000s as the Cadillac Catera, Chevy Caprice and Lumina, and the Pontiac GTO.
The F body might just be GM’s most famous platform. From 1967-2002, the F body was used exclusively for the Chevy Camaro and the Pontiac Firebird and Trans Am. The F body was based on, and shared many parts with, the X body.
As cars tended to grow smaller in the 1970s, GM introduced its first platform for subcompact cars. From 1971 to 1980 the H body was used for subcompact cars like the Chevy Monza, Buick Skyhawk, and Pontiac Starfire.
The K platform was a stretched version of the X platform. It was used for the Cadillac Seville from 1975 to 1979.
The Shift to FWD (with some Hold Outs)
1979 saw many of GM’s older rear wheel drive platforms start to change over to newer front wheel drive platforms. By this point all E bodies were FWD. GM also introduced the FWD T body for the international market. T bodies are still being sold overseas, but the 1988-1993 Pontiac LeMans was the only FWD T body sold in the US.
In 1980, the K body changed to FWD, where it was still used to build Sevilles. This K body was very similar to the E body. The K body was used for sedans, while the E body was used for coupes.
The X body was the next platform to join the K as FWD in 1980. The platform was used for compacts like the Buick Skylark and Chevy Citation from 1980 to 1985.
While other platforms were changed to front wheel drive versions, GM outright replaced the H body in 1981 with its FWD counterpart the J body. The J Body was meant to reduce engineering expenses for GM’s entry level models, by providing a shared platform across brands. It’s the only platform that had one model from each of GM’s five main brands: the Cadillac Cimaron, Oldsmobile Firenze, Buick Skyhawk, Chevy Cavalier, and the Pontiac J2000. The J body was used for the Pontiac Sunbird from 1985 to 1994 and the Sunfire from 1995 to 2005.
When the A body became FWD, some models associated with the platform remained rear wheel drive. These were renamed as the G body and included the Buick Regal, Chevy El Camino, and Pontiac Bonneville. These RWD G bodies were built from 1982-1988.
In 1983, GM struck a deal with Suzuki to import its supermini Suzuki Swift. GM sold the Swift, as well as its own rebadged versions, the Geo Metro and Chevy Sprint from 1983 to 2003. It designated these as the S body.
In 1984, Pontiac released the Fiero. Like the Corvair, the Fiero had its engine mounted behind the driver. Also like the Corvair, it differed from GM’s other offerings so much that it merited its own platform: the P Body. Fieros were built on the P body until 1988.
Chevy also introduced the fourth generation of the Corvette in 1984. Unlike previous Corvettes which had unique body-on-frame construction, the new one was designated as the Y body. Corvettes are still built on the Y platform today. From 2004-2009, the Cadillac XLR roadster was also built on the Y body.
When the C body changed to FWD, some models previously built on the C body remained RWD. These models, like the Cadillac Fleetwood and Brougham were moved to the D body.
The N body replaced the X body as GM’s platform for compact cars in 1985. It was originally engineered by Oldsmobile and was used by the Oldsmobile Calais, Pontiac Grand Am, and Buick Skylark until 1998.
From 1985 to 1992, GM brought in more rebadged Suzuki vehicles, like the Chevy Spectrum, Geo Storm, and Isuzu Impulse. Confusingly these were designated as the P body, even though that name was still in use for the unrelated Fiero’s platform.
In 1986, GM reintroduced the H body name. Where the original H body was for RWD compact cars, the new one was used for FWD, full size cars like the Buick LeSabre and Pontiac Bonneville. Many of these models had previously been built on the B body. The H body shared some parts in common with the C, G, and K bodies. It was built until 1999.
The L body joined the N body as another platform for compact cars in 1987. Where the N body was developed by Oldsmobile engineers, the L body was developed by Chevy engineers. It was eventually used for the Chevy Beretta and Corsica, until 1996.
From 1987 to 1993, GM built the Cadillac Allante, a high end luxury car. The Allante was designated as the V body, even though that name was already in use for unrelated international models.
In 1991, GM’s newly created subsidiary, Saturn, released its first cars, the S-series compacts. GM designated these as Z bodies. The Saturn Z bodies were built from 1991-2002.
Platform Consolidation and Experimentation
GM introduced a new G body platform, in 1995, to replace its several, existing large car platforms. As it did with the A and B bodies in the 1950s, GM had once again found itself with overlapping platforms. In the following decades it moved toward consolidating these over lapping platforms into new ones. The new G body was based on the K body used by Cadillac. It replaced the previous G body, as well as the K body, C body, and H body. Confusingly, models previously based on those platforms continued to use their old platform names in marketing materials, and in their VINs, even though they were being built on the new G body platform. The G body continued until 2011 in the form of the Cadillac DTS and Buick Lucerne.
From 1996-1999, GM briefly leased an electric car called the EV1. These were designated as the P body. GM considered the EV1 lessees participants in an engineering evaluation. Most EV1s were repossessed and destroyed at the end of the lease period, with a handful being donated to museums.
In 1998, a new platform was introduced to replace the N, A, and L bodies, and continue GMs simplifying of its line. Breaking with the alphabetic naming scheme, the new platform was known as the GMX130 platform. It was used for the Oldsmobile Alero and Chevy Classic, among others, until 2005.
As GM moved into the 21st century, it started using Greek letters to designate its new platforms. The first of these was the Sigma platform in 2002. The Sigma platform is GM’s midsized, rear wheel drive platform, used by Cadillac for the CTS until 2013, and for the STS. It replaced the V body Cadillac Catera.
The Delta platform replaced the T, J, and Z platforms as the basis for compact cars and crossovers. It has been used since 2003 for models like the Chevy Cobalt and Cruze, Pontiac G5, and Saturn Ion. It is still in use.
In 2006, GM’s Australian subsidiary, Holden, developed the Zeta platform, as a replacement for the V body. The Zeta platform is sometimes called the “Global RWD Architecture.” Many Holden models are based on it, as well as the Pontiac G8, and the Chevy SS. It is also used for the fifth generation Chevy Camaro, which makes the Zeta platform the successor to the F body as well as the V body.
2006 also saw the release of n a pair of roadsters from Pontiac and Saturn, the Solstice and Sky, respectively. These were built on the Kappa platform. The Kappa platform was short lived, only lasting until 2009.
If you’ve made it this far, congratulations. You now know all about GM’s different body platforms. Admittedly, this subject can get pretty complicated at points. You can see why GM’s recent trend has been to consolidate its platforms. That, thankfully streamlines their product lines, which, after all, was the whole point of sharing these platforms in the first place.
Written by Dan Smolinsky.