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 Cuts $600 Million Off Ad Spend -- Yes, Really Automaker Says It's Less Than TNS Reported, but Media Owners Still Got Burned By Jean Halliday, Published on February 12, 2007 4 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.