BMW AG on Thursday is to announce major changes for its US plant in Spartanburg, South Carolina, Automotive News reported.

The newspaper said that BMW's US manufacturing subsidiary, which builds the new Z4 roadster and X5 sport wagon, is expected to announce the investment of more than $400 million to increase capacity - possibly by adding a third model.

Last year, BMW sought state regulatory approval to increase air emissions from the plant, a move intended to cover needs that were not spelled out in the regulatory permit, Automotive News said.

And, earlier this year, BMW appealed to the South Carolina legislature to adopt a funding mechanism that would allow the state to provide financial incentives on plant expansions, the newspaper said.

Automotive News said that South Carolina officials have since said that a BMW expansion representing an investment of at least $US400 million and the hiring of 400 additional workers would trigger a state incentives package worth $80 million.

But until Thursday, the company will not reveal what it intends to do at the plant, a spokeswoman told Automotive News.