GM’s Sigma platform which has spawned a handful of sporty and comfortable rides for Cadillac is starting to grow long in the tooth and will soon be obsolete, especially now that the STS is no longer with us, the SRX has moved to a crossover platform and the next-gen CTS is adopting the lighter and more flexible Alpha platform.

It turns out GM is already working on a replacement for its Sigma platform, one that will spawn a number of large, rear-wheel drive models including a replacement for the XTS as well as the long-rumored Caddy flagship.

The new platform, according to Car and Driver, will be called the Omega.

Being named after the last letter of the Greek alphabet is entirely appropriate for the new platform as it will spawn some of the biggest models in GM’s passenger vehicle lineup, but it will still pick up many elements from the smaller Alpha design to provide greater economies of scale.

This will allow engineers to keep the platform light as well as flexible enough for a variety of bodystyles. It will also mean that Omega-based cars could potentially be built on the same production line as Alpha vehicles, once again helping to reduce cost while improving flexibility--it appears GM has learnt some lessons from its key rivals Toyota and Volkswagen.

In terms of size, Omega-based cars can range from something slightly larger than a BMW 5-Series to something a few inches longer than a long-wheelbase 7-Series. There’s word that a large crossover model could also be developed for Cadillac, though it’s unclear how this particular model would fit in with a planned seven-seat Lambda-based crossover and next-gen Escalade, which will be keeping its truck roots.

As for the cars we can expect, the first is likely to be a rear-wheel drive sedan slightly larger than the XTS due in about two years. It will either be sold alongside the XTS or replace it altogether and will serve as Cadillac’s range-topper until a true, slow-cooked flagship is developed. GM is not fully committed to launching a big sedan in the vein of 2003's Sixteen concept as its flagship, meaning we could see a mega-coupe or convertible designed along the lines of last year’s Ciel concept launched instead.

One thing’s for certain, Omega will be reserved for premium vehicles only. Other large, rear-wheel drive models are expected to be built around the Zeta II platform, which is currently being developed in Australia and will debut in the next-generation Holden Commodore around 2016. Zeta II is expected to feature in some Chinese-market Buick sedans and may even be manufactured here in the U.S. by Chevrolet.

2003 Cadillac Sixteen Concept

2003 Cadillac Sixteen Concept