Fiat and General Motors on Monday declined to comment on a Financial Times (FT) report that said GM believes legal problems make invalid its promise to buy the Fiat Auto unit from next year, Reuters reported. The news agency said GM may be forced to buy the remaining 80% of Fiat's loss-making car unit it does not already own from 2004, which many analysts had held on to as a last-ditch chance for the industrial group to pull free from its loss-making car business.