MIT's Sloan School of Management has found that auto buyers trust the recommendations of an automaker-sponsored Web site if it's clear that the site will recommend competitors' vehicles. MIT professor Glen Urban calls this approach trust-based marketing. Vincent Barabba, GM's general manager of corporate strategy and knowledge development, will detail the automaker's experience with trust-based marketing this week at a conference in Cambridge, Mass., sponsored by the Center for eBusiness@MIT. "By sponsoring a site that would recommend a competitor's vehicle," Urban says, "GM is saying, 'We might lose a customer because of a recommendation, but the information we gather about what people want will help us develop the best cars of the future.'"