Federal highway safety officials said on Thursday the agency has opened or upgraded probes into more than 530,000 vehicles made by DaimlerChrysler AG's North American unit, Ford Motor Co. , General Motors Corp. and Kia Motors Corp. The U.S. National Highway Traffic Safety Administration (NHTSA) in its latest monthly defect report said it had opened probes, or preliminary evaluations, into cars made by Chrysler, Ford and Kia, and upgraded a GM probe to an engineering analysis.