Fiat CEO says time not right to list Auto unit

* Fiat to unveil new business plan by Q1 2010 * Mergers will continue, but with different management style * Opel decision was totally justified * Marchionne says most of UBS problems solved (Adds more comments) ZURICH, Nov 6 (Reuters) - Fiat boss Sergio Marchionne, on his way back from unveiling a new strategy for Chrysler in Detroit, ruled out listing Fiat Auto, an option Fiat considered earlier this year when it was hoping to take over carmaker Opel. Marchionne also said Fiat would present a new business plan by the end of the first quarter of 2010. A listing of Fiat Auto "will be done when it is the time (to do it). It is not the right time (now)", he told reporters on the sidelines of an event organised by the Italian-Swiss Chamber of Commerce in Zurich. Asked about consolidation in the car-making sector, he said mergers would continue but they would require that management understood another country's culture to be successful. "If we are able to do that, the era of mergers will continue. But they will be different mergers; they won't be about 'domination', but about industrial entities that need to come together." Marchionne also said General Motors' decision to keep its European unit Opel was "totally justified". Marchionne, also outgoing non-executive vice Chairman at UBS AG, said he believed the bulk of the Swiss bank's problems had been resolved. "Not all, but the major part of the problems have been resolved," he said. (Writing by Lisa Jucca and Nigel Tutt, editing by Will Waterman)