As previously stated here on Autoblog, the revolutionary Spring Hill plant's future has become quite murky as Saturn product moves elsewhere. Once the crown jewel of GM's North American operations for its broad and diverse list of competencies (including aluminum casting and large-scale plastic injection molding) and unique union contract, it's currently slated to receive a $400 million upgrade starting in November. It's stated that changes will include the ability to accommodate larger vehicles with steel body panels. Additionally, GM plans to implement their C-Flex bodyshop, allowing the production of vehicles on several different platforms. What does all this mean? GM obviously intends to build something other than Saturns here, but whether it's Lambda-based crossovers, minivans, or the much-rumored new RWD sedans and coupes remains to be seen. It's thought that Saturn Hill can produce about 400,000 vehicles per year, meaning that it'll likely take a variety of products to utilize the plant's full capacity.