TL*THE CONTACT OWNS A 2007 CHEVROLET IMPALA. THE CONTACT STATED THE VEHICLE WOULD NOT START AND THE FAILURE OCCURRED INTERMITTENTLY AFTER DRIVING THE VEHICLE. THE CONTACT STATED THE VEHICLE WOULD OFTEN TAKE UP TO ONE OR TWO HOURS BEFORE IT WOULD START. THE VEHICLE WAS TAKEN TO A DEALER AND AN INDEPENDENT MECHANIC WHERE THE TECHNICIANS WERE UNABLE TO DIAGNOSE THE FAILURE. THE VEHICLE WAS NOT REPAIRED. THE APPROXIMATE FAILURE MILEAGE WAS 75,000.