The Ford Motor Company agreed to add 12,000 jobs and invest $6.2 billion in its United States plants in a new four-year labor contract with the United Automobile Workers union, the company said Tuesday. Ford said the numbers included 6,250 jobs and $2.4 billion in investment that it had previously announced. The U.A.W. planned to provide more details at a news conference scheduled for later Tuesday. We really believe that it’s fair to our employees and recognizes the contribution that they’ve made to the success of Ford Motor Company,” John Fleming, Ford’s executive vice president of global manufacturing and labor affairs, told reporters at Ford’s headquarters. “But we’re also pleased that it will continue to improve our competitiveness directly here in the United States.”