Starcom was the incumbent on the US business where the bulk of GM's spend is focused and where it owns the Buick, Cadillac and Chevrolet marques. Carat adds this business to the GM account in Europe, which it has held since 2007, and where GM manufacturers Vauxhall and Opel.
The appointment covers US, EMEA and Asia Pacific but does not include Brazil, India and China which were not included in the review. GM is understood to have launched the process to improve the effectiveness and efficiency of its global media.
Aegis Media, Carat's parent, claims it is the largest in its history and it is understood that Carat is looking to set up a new office near the Detroit-based headquarters of GM in order to service the business.
Joel Ewanick, the GM Vice President and global chief marketing officer, led the review. He said: "We wanted a media agency partner with the sophistication to leverage global marketing opportunities. They are uniquely positioned to help us form strong media partnerships and drive significant global efficiencies."
Jerry Buhlmann, the chief executive officer of Aegis Group, said: "We are extremely proud to have been selected by General Motors as their global media partner, for what is the most significant new business win in Aegis Group’s history.
"This win reflects Aegis Media’s unique ability to deliver integrated and specialist media and digital communications services on a global scale. We are excited about developing our relationship with GM in the future, and look forward to delivering many years of innovation and value to GM, our largest global client."
Publicis Groupe, the parent of Starcom, issued a statement to say that the GM/Starcom relationship represented less than 0.5 per cent of total annual Publicis revenue.
The statement added: "We’re proud of the insight and high level of professionalism that Starcom has brought to its work on GM’s image over the years, and of the support that we’ve given to GM through many ups and downs. Starcom will serve GM to the end of June."
Nigel Morris, chief executive officer of Aegis Media Americas, said: "This is a defining moment for our business and the market. We have designed our organization for convergence and globalization. We have a clearly differentiated operating model that is focused on reinventing the way we work with our clients and their brands.
"From the outset it was evident that the GM team was looking for a transformative approach with innovation at the core. They have a powerful vision and powerful brands and we are looking forward to it being a powerful partnership."