General Motors Corp. will invest $225 million in its soon-to-be-idle Spring Hill (TN) plant, but the auto maker doesn’t tip its hand on which vehicles will be built there.

The money, which will be used to renovate the paint shop in preparation for future vehicles, is contingent on tax incentives from the state of Tennessee, the auto maker says.

The plant project is welcome news to plant workers, who will be without a product in March when GM halts production of the Saturn Ion, replacing it with the Adam Opel GmbH-based Astra, which is made in Antwerp, Belgium.

The Saturn Vue cross/utility vehicle, built on Spring Hill’s No.2 line, also will cease production next year. A redesigned Vue for the ’08 model year will be produced in Ramos Arizpe, Mexico.

Last month, GM also nixed plans to build front-wheel-drive minivans based on its Midsize Crossover Architecture (Lambda) at the Spring Hill plant.

A GM spokesman says management has yet to decide on the next product for Spring Hill.

However, Troy Clarke, GM North America president, recently told Ward’s the United Auto Workers union leadership at Spring Hill has been “made aware” of additional models the auto maker plans to produce at the facility.

“A public announcement is forthcoming,” Clarke said at the time.

Clark also recently said the auto maker will make several investments in 2007 to increase production flexibility in domestic plants.

GM says Spring Hill will be idled for several months after the renovation work begins in April and that the company still is reviewing when the hourly workforce will return to work.

Represented by UAW Local 1853, the Spring Hill assembly plant employs about 3,500 hourly and 230 salaried workers. The facility has produced more than 3.4 million vehicles since it first started manufacturing cars on July 30, 1990.

– with Herb Shuldiner