General Motors Corp.'s Pontiac-GMC division dismissed McCann Erickson Worldwide, an agency that has been creating advertising for GMC trucks, vans and sport utility vehicles for nearly four decades. Ammirati Puris Lintas, which had been BMW's ad agency for years and positioned the import as the "Ultimate Driving Machine," was named Wednesday as the new agency for GMC. Detroit-based GMC has seven models on the market, ranging from the Jimmy compact sport utility vehicle to the full-sized Savana van and Sierra pickup truck, and plans to introduce two more sport utility vehicles early next year. General Motors merged its Pontiac and GMC divisions earlier this year and was repositioning GMC as a premium brand. Division officials declined to disclose how much is spent on GMC advertising each year, but some trade reports have estimated it at about $70 million. McCann had been GMC's agency since 1958 and continues as the agency for another GM division, Buick. Pontiac-GMC also announced that the agency DMB&B held onto its job as the agency for the Pontiac brands after an agency review.