With all this talk about the solstice, I've been thinking about future gm platforms. It's been discussed over and over again about the sigma platform and what it will underpin. Originally it was supposed to only be used for cadillac. There was also talk about a "smaller" sigma platform called sigma light. I remember reading that in some magazine month's back.

Does anybody know anything about this?

 

"Sigma-lite" refers to a lower cost, higher volume "Sigma" chassis.

 

Isn't "Sigma-lite" a bit of a misnomer tho? The Sigma chassis is not being used outside of Sigma cars, but parts of it's suspension design are ...

 

GuionM are sigma light and VE the same or different? I remember you had heard mid lux and assumed it was VE but it turned out to be an evolution of the W body. Any guesses as to the relationship between Sigma/Sigma Light/ and VE?

 

It's all but official that VE will be running Sigma (or Sigma style) suspension. Not sure if the chassis for VE will be a clean sheet, an adaptation of Sigma, or an enhancement of the existing V-car platform. I hope it isn't the latter ... that chassis design is 25 years old now ...

 

When the next Camaro comes out, it will be called an F-body, even though it has nothing in common with the last F-car. Same goes for the V-body.

Instead of using model years to designate progressive cars ('02, '04, ...) Australian cars use the alphabet (Ford of Australia also does this. It currently makes the BA Falcon). The Holden will be the VE (V body, E series). That's all the VE designates. That haven been said, it's probally wrong to call a car made here a VE, since it's not a Holden.

Sigma is the CTS, STS, SRX. Primarily a set of components such as suspension assembly, floorpan, front end structure.

Sigma-lite, or GM's "Volume" RWD chassis is supposed to be a lower cost version of Sigma. Perhaps stamped steel suspension pieces instead of forged alumunum, perhaps slightly different geometry to make up for the different pieces, perhaps a lighter or differently designed engine and rear suspension cradle, again to compensate for different cheaper or lighter pieces.

I once thought the VE was the V-car with Sigma parts worked in, but it's going to be more of a Sigma made in a more economical (cheaper) way.

 

I would just like to interject something here. Probably will confuse everybody.
Looking at GM's monthly production schedule, they list all their cars, which plant these cars are built at, AND the "body code".

So although the CTS & SRX are built off of the Sigma chassis, they still have separate distinct "body codes".

According to GM, the CTS has a body code of "D". I guess that would make the CTS a D-body.

And the SRX carries the body code of 265. I assume then that we can consider the SRX a GMT-265.

It will be interesting to see what "body code" they give the STS when it comes out.

 

I should have included that as well.

Sigma isn't a body. It's the name given to components, and perhaps shared structure. Bodies have their own designation.

Ford has the perfect example. Although the Thunderbird shared many of it's components and body structure with the Lincoln Mark VII, the Lincoln wasn't called an MN12, like the Thunderbird and Cougar.

Like HuJass pointed out, the STS (though it will be a CTS in many areas) will have a different body designation.

 

Not sure on SRX'S code, (the 265 part) but I am almost positive that it'd be GMX-265, not GMT-265...

If I am correct, GMT-xxx are trucks, GMX-xxx are cars, for example, Cobalt is GMX-001.


Just a minor detail, but worth pointing out...

 

Darth,
If you go to GM's own site, they have the SRX production listed under trucks. Hence the GMT prefix.

So it looks like Sigma, Delta, Epsilon, etc are the names of the BASIC structural architecture.
The actual vehicle still is given a body code like the old days. My guess is that if 2 cars existed with the EXACT same frame and underpinnings, they would get the same body code.

And I'm guessing but I would assume the GMX identifiers serve the same purpose as the body code but are used internally.

 

Ah... well, that is possible then.

Damn crossover vehicles confuse the hell out of me sometimes!

 

See, this is what gets me. Look underneath a 6th- or 7th-gen Honda Accord sometime. There's some pretty damn trick suspension components - lots of nice tubular steel and cast aluminum bits, the kind of stuff that's light and stiff. Interestingly enough, '96-'99 GM 3/4- and 1-ton trucks also avoided the use of stamped-steel suspension members and instead had ductile cast iron and tubular steel suspension arms. How do you afford this stuff? Volume, of course.

So, if the economies of scale work for those two examples, what not for Sigma Lite? Seems that the combined volumes of Sigma and Sigma Lite platforms would be substantial, and the use of common components would greatly benefit both platforms.

Oh well - I'm sure by the time things are said and done, they'll end up being two completely different platforms. That seems to be the way things go once the cost-cutting gains speed.