For some time now General Motors has been planning to shift their big sedan models such as the Chevy Impala from their current front wheel drive configurations back to rear wheel drive. The Zeta platform that will form the basis of the new Camaro and Pontiac G8 was supposed to spawn a new Impala in 2010. However the shifting sands of oil prices and new fuel economy regulations may cause a shift in plans. While the current Impala sold almost 300,000 units last year some projections for a new rear drive model put sales as low as 100,000-130,000 per year. All of this is causing GM to reconsider their plans and put the new car on a stretched version of the new Epsilon II front wheel drive platform. The new platform is being engineered for use globally in a wide variety of lengths and widths. Regardless of which direction GM goes it will have to decide soon if it's going to make a 2010 production target.
[Source: Automotive News - Sub. req'd]