Chicago's most important introduction this week was the Pontiac G8 sedan. (See Motor Trend's video.) In fact, it may be more important than GM's Detroit introductions, the Cadillac CTS, Chevy Malibu and Camaro convertible.

It's the G8 that makes the Camaro possible. They're both on the same new rear-drive platform, designed and engineered in Australia at GM's Holden division.

The car is so important because...

a.) It validates the move back to big rear-wheel-drive sedans that Chrysler began with the 2005 LX models.

b.) It provides GM with an affordable rear-drive platform that can be used across most of its divisions. Cadillac's Sigma premium rear-drive platform is too costly.

The Holden rear-drive architecture, formerly known as Zeta, has a MacPherson strut front suspension and a multi-link suspension in the rear. Chief car guy Bob Lutz says it's extremely flexible, able to underpin a wide variety of cars. GM has developed it with 112-inch (Camaro), 115-inch (G8/Holden Commodore) and 119-inch wheelbases. The next-generation Buick Lucerne and Cadillac DTS replacements could run off that 119-inch wheelbase, although GM claims it hasn't made a decision about what to do with those cars.

The G8 is a performance sedan designed to target the Dodge Charger. The base G8 will come with a 261-horsepower, 3.6-liter twin-cam V-6 and five-speed automatic, aimed at the 3.5-liter V-6 Charger. The G8 GT will have a 362-horse 6.0-liter small block V-8, targeting the Hemi Charger R/T. It will come with the choice of a six-speed automatic or six-speed manual, and - thank the car gods - has a handbrake instead of a pedal-operated emergency brake. Of course, a 600-horse Z06 engine would nicely vanquish the Charger SRT-8, and take on the BMW M5 as well.

Styling is pre-Bangle BMW-esque, nicely updated, and while GM is careful not to make claims about how well the car handles, BMW's 5 Series served as the benchmark for steering and handling.

The 2008 G8 is scheduled to go on sale early next year.