GMI Platform Guide
Last Updated: March 16, 2006
Delta
The Delta platform in GM’s premium front wheel drive small car platform. Fi
rst introduced on the Saturn ION (to not-so-rave reviews), Delta is now comi
ng into it's own under-pinning Chevy's new Cobalt small car. Suspension wise
, Delta uses a independent front, and twist beam rear setup with various sta
tes of tune depending on the application. Pretty much every flavor of GM's E
cotec I4 is offered with the Delta, starting with the base 145 HP 2.2L Ecote
c and being punctuated with the supercharged 205HP 2.0L Ecotec (ION Redline
and Cobalt SS). Transmissions include a 4 speed automatic, and 5 speed manua
l. The ION Redline and Cobalt SS receive a specially tuned version of the 5
speed manual. Currently the Delta platform underpins the Chevrolet Cobalt, C
hevrolet HHR, Pontiac G5 Pursuit, and the Saturn ION.
Things to know-
●GM benchmarked VW's last generation Jetta when designing the new Cobalt.
●The high end Cobalt SS and ION Redline are the performers of the platform,
featuring not only great straight-line   performance, but decent handling.
●Saturn was going to get an all-new Delta car (GMX-002) in 2008, but the pr
ogram was canceled.
Kappa
Kappa is GM’s small rear-wheel drive platform for mid-performance cars. Th
e platform debuted on the  Pontiac Solstice, followed by the Saturn Sky and
Opel GT. As of right now the Kappa is a low-production platform, but that co
uld change to underpin some much-needed sport-compact cars for GM. Like the
Delta platform, the Kappa is capable of acquiring all of the Ecotec 4-cylind
ers mated to a specially-tuned 5-speed manual and all Kappa’s are carried b
y independent front/rear suspension with a near 50/50 weight distribution.
Things to know-
● Solstice GXP and Saturn Sky Redline performance Kappa’s are set to arriv
e with a turbocharged Ecotec 2.0L in 2007.
● Kappa allowed GM to enter the roadster market.
● A Pontiac sport-compact could be a future Kappa candidate.
Epsilon
The Epsilon was introduced in the United States in 2004 and is GM’s bread-
and-butter sedan platform. Epsilon is able to be powered by nearly all of GM
’s V6 family, plus the Ecotec 4-cylinders mated to 4-speed automatic transm
issions (hopefully 6-speed soon!). The platform is used worldwide, for the S
aab 9?, Opel Vectra and Cadillac BLS (Europe only). State-side the platform
underpins the Chevrolet Malibu, Pontiac G6, and Saturn Aura. All Epsilon veh
icles employ 4-wheel independent suspension.
GM also utilizes an extended version of the Epsilon. That version of the pla
tform is used on the Chevrolet Malibu Maxx, Pontiac G6 and Saturn Aura.
Things to know-
● Pontiac G6 is will be available in coupe and hard-top convertible version
s.
● An updated version of the Epsilon will debut with an all-new Saab 9-5.
Epsilon II
The replacement platform for the current Epsilon platform is going to be the
ultimate global platform for General Motors. It will be utilized for use ar
ound the world; in Europe, North America and possibly in other markets after
the platform goes online. Epsilon II will likely be slightly larger than th
e current Epsilon, however it will be more versatile and be all-wheel drive
capable. E-II will debut in 2009 on the Saab 9-5.
Things to know-
●There were rumors that E-II would be FWD/RWD/AWD capable. That has not bee
n confirmed, however it is likely that they can tune the AWD to send more po
wer to the rear wheels for more performance-oriented handling.
Y-Body
The Y is GM’s super performance chassis. Occupied by only the Chevrolet Cor
vette and Cadillac XLR, it is geared to perform. The rear wheel drive Y-body
employs a four wheel independent suspension and an innovative drive train l
ayout. The Y-body uses a drive train layout where the engine is mounted long
itude-wise in the front, as on most RWD cars, however the transmission is mo
unted in the back as a transaxle. Power is then transferred via a central to
rque tube.
The Corvette is powered by means of nothing other than GM’s family of small
-block V8’s. Corvette ZO6’s are now powered via a hand-built 500-hp small-
block. Cadillac’s XLR is powered by their Northstar V8, both a supercharged
version and non-supercharged are used. There is and 6-speed automatic and 6
-speed manual offered.
Things to know-
● Y-Body is one of the best platforms in the world.
● Don’t expect to see this platform obtainable on any other GM vehicles
W-Body
Also known as the ‘mid-lux’ platform, the W-body is one of the most used p
latforms in GM’s stable. It currently supports the Pontiac Grand Prix, Chev
rolet Impala, Chevrolet Monte Carlo and Buick LaCrosse/Allure. Approximating
the Epsilon, all of GM’s V6 powertrains can be used on the W-bodies amid 4
-speed automatics. Performance W-bodies now use a 5.3L small-block V8 that i
s mounted laterally. All mid-lux cars have 4-wheel independent suspension.
Things to know-
● The W-Body is likely on its last generation of use.
● There are rumors that the platform will be replaced by the ‘Chi’ platfo
rm.
Sigma
The Cadillac-only platform underpins the rear-wheel drive CTS, STS, and SRX.
The Sigma vehicles use a 4-wheel independent suspension design that utilize
s a short/long arm, coil over strut with anti-sway bar in the front, and a m
odified multi-link with anti-sway bar. Of course, Sigma vehicles use GM’s h
igh-end V6’s and Northstar V8’s mated to 5-speed automatics or manual (in
CTS).
Things to know-
●Sigma is widely liked by the media for being a solid, well-mannered chassi
s.
●Even two years after launch, the SRX is considered the best-driving luxury
crossover on the market.
G-Body
The G is used for the Cadillac DTS and Buick Lucerne. All G cars use GM Push
rod V6’s or Northstar V8’s transferred through 4-speed automatics. The fro
nt-wheel drive platform sports 4-wheel independent suspension, however the D
TS features Continuously Variable Road-Sensing Suspension (Delphi's Magnetic
Ride Control) that reads the road for changing conditions within millisecon
ds.
Things to know-
● Before the announcement of the Lucerne, the G-Body’s future was uncertai
n.
● The dying Pontiac Bonneville was also a member of the G-Body family.
Truck Platforms
M-Body
M-Body is the basis for the Pontiac Vibe, and is a joint platform with Toyot
a. The Vibe itself is built alongside the Toyota Matrix, which also utilizes
the M-Body. The only powertrain is a 1.8L VVT-i mated to a 4-speed automati
c, 5-speed manual or 6-speed manual. The Vibe is supported with front indepe
ndent suspension among rear torsion beam includes front and rear stabilizer
bars.
Things to know-
● It is hard to tell what the future of the M is because of the Toyota part
nership.
● The Vibe shares many components and parts with its Toyota cousin.
Theta
The unibody crossover platform holds-up the Chevrolet Equinox, Saturn Vue an
d Pontiac Torrent. Theta’s have front/rear independent suspension and are p
owered by a 4-cylinder (Saturn Vue), a Honda V6 (Saturn Vue), or GM’s ‘goo
d-ole’ 3400 V6 (Equinox and Torrent). All of which use a 5-speed automatic,
however the Vue can be had with a 5-speed manual or a specially tuned 5-spe
ed manual in the Vue Redline.
Things to know-
● Theta is such a good platform, Cadillac may use it for a future crossover
!
● Expect the platform to be used for quite awhile.
GMT-355
This architecture is used for the Chevrolet Colorado, GMC Canyon and Hummer
H3. The Colorado and Canyon come standard with GM’s I-4, but all of the veh
icles use GM’s Vortec I-5 powertrain, along with a 4-speed automatic or 5-s
peed manual.
Colorado and Canyon models use A-arms and a 28mm front stabilizer bar. Firme
r urethane jounce bumpers are used on all Z71 models in place of the softer
rubber bumpers used on the Z85 2WD Suspension. Both Z71 2WD and 4x4 have fro
nt torsion bars that help supply performance, handling and stance. The H3 us
es front independent suspension with multi-leaf rear suspension.
Things to know-
● The GMT-355 could be the basis for a Jeep Wrangler competitor.
● There are rumors that a V8 will hit in the 355 vehicles.
Lambda
General Motors has made it clear that they want a very large piece of the cr
ossover market. Lambda-based vehicles will be crossover vehicles that are sl
otted between midsize and large. The first Lambda to arrive will be the Satu
rn Outlook, followed by the GMC Acadia and Buick Enclave. After the current
minivans are done, their Chevrolet and GMC replacements will be Lambda-based
as well.
Things to know-
●Hybrid versions of the crossovers are possible.
●The Lambda program has been over-budget.
GMT-360
GM’s midsize SUV platform underpins the Chevrolet Trailblazer, GMC Envoy, B
uick Rainier, Isuzu Ascender and Saab 9-7x. All of the GMT-360’s are powere
d by GM’s I-6 or 5.3L V8 with Active Fuel Management. For 2006 the Trailbla
zer will get a dose of SS with an optional 390 HP LS2 V8 (standard on SSR).
Suspension wise the Trailblazer and Ascender have front independent with a f
ive-link rear, while the rest of the 360’s have front independent with load
-leveling air suspension in the rear. The only transmission available is a 4
-speed automatic.
Things to know-
● GMT-360 has an uncertain future.  With competitors like Ford and Daimler
Chrysler thinking about moving their midsizers to unibody platforms, GM is c
onsidering the same.
GMT-800
This is the most-used platform in the world, underpinning the Chevrolet Silv
erado, Chevrolet Avalanche, Chevrolet Tahoe/Suburban, GMC Sierra, GMC Yukon/
Yukon XL, Cadillac Escalade/EXT/ESV, and Hummer H2. All of the 800’s use GM
’s family of Vortec V8’s or Duramax diesels mated to 4-speed automatic tra
nsmissions.
Things to know-
● This is one of the most rugged platforms in the world.
● GMT-800 vehicles have made it through the ultra rugged Humvee test course
.
GMT-900
When the GMT-800 platform retires in 2007, this will be its successor. Under
pinning all of the vehicles the GMT-800 currently does. It too will use Vort
ec V8’s and Duramax diesels. Along with new 6-speed automatic transmissions
, a new 6.0L hybrid using GM’s new two-mode system will become available.
Things to know-
●A new, fully boxed frame that is significantly stronger and stiffer with h
ydro formed front and rear bay sections.
●Wider front and rear tracks – approximately 3 inches (76.2 mm) in front a
nd 1 inch (25.4 mm) in rear – enable increased stability, as well as a smoo
ther, more controlled ride.
●New coil-over-shock front suspension delivers linear, responsive ride and
handling characteristics.
●Highly refined five-link rear suspension (with variable-rate springs) deli
vers damped, isolated road feel and supports a variety of load-carrying capa
bilities.
●Use of monotube Autoride shock absorbers for more controlled, real-time da
mping capability.
●New rack-and-pinion steering system delivers precise, responsive steering
and contributes to the vehicles’ “drive small” feel.
●All-new four-wheel disc brake system larger vented discs, stiffer calipers
, more robust apply system and standard next-generation Bosch ABS system pro
vides shorter stopping distances, better pedal feel and quicker brake respon
se.
●Larger-diameter standard and available wheels and tires, including segment
-largest, 22-inch designs available on Cadillac Escalade.
●Standard StabiliTrak electronic stability control with first-time GM appli
cation of rollover mitigation – a software algorithm technology that uses s
ystem sensors to proactively predict vehicle “tip-up” and applies appropri
ate brake forces to prevent rollovers.
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