You’ve read all of your free items this month. To register, get added benefits and unlimited access to articles, Become a Member. Already a Member? Sign in. Advertising Age Article Abstract GM Roars Forward Into Digital Ad Channels Changes at Dedicated Media Shop Lay Groundwork for Auto Giant to Shift Spending to Encompass Multiple Online Channels By Jean Halliday, Published on March 17, 2008 1 Want more Access, Content & Connections? Upgrade to Membership. We are glad you are enjoying Advertising Age. To get uninterrupted access and additional benefits, become a member today. Become a Member Already a member? Log in.