Effective Sept. 1, Bill Gibson assumes the role of interim fleet and commercial sales manager at General Motors Fleet and Commercial Operations, plus he continues his existing responsibilities for rental and fleet management company sales and support. Gibson joined General Motors in 1973 in manufacturing operations. In addition to his 10 years experience in fleet, Gibson has worked on the corporate financial staff. Jim McCallum, who recently moved back to Fleet and Commercial as the director of global fleet sales, also is taking on more responsibilities. In addition to his global duties, McCallum will develop programs to enhance and support sales growth for commercial and fleet dealers. McCallum has spent the majority of his 30-year career in fleet and commercial sales and marketing with Chevrolet.These moves were made due to the promotion of John Larson to director of finance for the entire Vehicle Sales, Service and Marketing organization. Larson, who had just begun his third stint in Fleet and Commercial as the director of fleet and commercial sales, succeeds Jack Hazen, who has been named director of finance for recently named Vice Chairman Bob Lutz.