Toyota Motor Corp and the joint venture plant it operated with General Motors Co have reached a $6 million settlement with former workers at the now-shuttered California factory. The payment settles a lawsuit brought by workers who were on medical leave when the San Francisco-area plant shut in March 2010. They claimed they received smaller severance payouts than other workers received. The settlement announced on Thursday represents one of the last complications from Toyota\'s decision to close its only US plant where workers were represented by the United Auto Workers union. The plant opened in 1984 as a joint venture between GM and Toyota. The factory was the first auto manufacturing plant in the US for Toyota, and it gave GM a chance to study its rival\'s vaunted lean manufacturing system.