General Motors Corp. breaks a new 60-second TV spot for its GM Card tonight in an estimated $8 million push that will air on national cable through yearend. The spot prominently features an 800-number in a drive to attract more members. In the spot, two men vying for a restaurant check compare the benefits of their different credit cards. Mullen
, Wenham, Mass., handles. Copywriter: Richard DeCrefcenzo. Art director: Bill Gustat.