General Motors’ RWD Zeta platform was pioneered in Australia for the locally built Holden Commodore sedan but right from the start Detroit had global intentions for the design. Today, Zeta running gear can be found in models sold in China, South Korea, the UK, and in North America, but GM has much more ambitious plans for the platform, going right up until 2020.

Back in March we reported that the platform would be modified to be smaller and more fuel-efficient, and that the first car to ride on this ‘Zeta II’ design would be the next-generation Holden Commodore due in 2013. A new report published by GoAuto confirms that Holden is developing a lighter and more highly-evolved version of the three-year old Zeta platform.

Holden insiders have revealed that cutting weight is one of the primary goals for engineers, but also to eventually use Zeta for medium RWD cars as well as large ones. One key element will be the increased use of lighter materials in its construction, including the possibility of advanced composites. Other issues affecting the design process include the use of more fuel-efficient powertrains, such as diesel and hybrid options, as well as increased global production.

Some of the recipients for the updated platform include Cadillac and Chevrolet in the U.S., Buick in China, and Holden in Australia. One thing is for certain, GM will keep its premium Sigma RWD platform, currently used by Cadillac, as well as the relatively low-cost Zeta for its future models.

Where this leaves rumored development plans for a smaller ‘Alpha’ RWD platform and a premium Cadillac architecture is anyone’s guess, however, given GM’s financial woes it’s unlikely that such an expensive undertaking is high on the company’s priorities.