Vauxhall chairman Nick Reilly has been promoted to vice president sales, marketing and aftersales for General Motors Europe.
He will lead a review of strategies following the decline of GM's market share for cars and light commercials in Europe to just over 10%.
“I will apply my experience gained over the past five years leading Vauxhall, though the market must be assessed separately in each country,” he said.
On August 1, Mr Reilly replaces Jeffrey Hurlbert who returns to the US before retiring next year.
Mr Reilly, who remains chairman of Vauxhall Motors, is replaced as managing director by Kevin Wale, operations director for GM Asia Pacific.
Following an AM comment in the June 22 issue, Vauxhall has emphasised that Ian Coomber's retirement decision was entirely his idea.