Vauxhall boss Nick Reilly, promoted to head sales, marketing and aftersales for General Motors throughout Europe, will lead a wide-ranging review of strategies.
GM's market share for cars and light commercials in Europe has slipped to just over 10%. "We have to find ways of restoring gross profit margins," he told AM-online.
"I will apply across Europe my experience gained over the past five years leading Vauxhall, though the market must be assessed separately in each country."
From August 1, Mr Reilly will be vice president sales, marketing and aftersales, replacing Jeffrey Hurlbert who returns to the US on "special retirement" before retiring next year.
Mr Reilly, who remains chairman of Vauxhall Motors, is replaced as managing director by Australian Kevin Wale, who for three years has been GM's operations director for GM Asia Pacific, based in Singapore.
He said: "We need to look at developing different ways of getting cars to market in Europe, including use of the internet."
Mr Reilly, who will be based in Zurich, Switzerland, said he would pay regular visits to the UK where he was recently appointed president of the Society of Motor Manufacturers and Traders.