Three General Motors units posted a combined 25.6% hike in second-quarter earnings. General Motors Acceptance Corp., GM's lending arm, said profit rose 37.9% to $411.8 million. Hughes Electronics, parent of Hughes Aircraft and Delco Electronics, recorded a 4.7% increase in earnings to $178 million. Electronic Data Systems' earnings climbed 14.8% to $72 million. Hughes profit rose despite a 5% drop in sales because of increased earnings by Hughes Aircraft's missile group and cost cutting.