FRANKFURT (Reuters) - General Motors
"We respect Alfred Rieck's decision and wish him all the best for his professional future," said GM Vice Chairman Steve Girsky in a statement on Friday.
The carmaker is battling a slump in car sales in Europe due to the weak economic climate, which has squeezed consumer spending.
When Rieck was appointed as sales chief for Opel and its UK sister brand Vauxhall in July, first-half volumes in its core European Union market were already down 15 percent, according to figures from Europe's automotive industry association ACEA.
In the second half, Opel and Vauxhall sales declined at a slightly faster pace, resulting in an overall 15.8 percent drop to about 816,000 vehicles for the full year. The carmakers combined market share shrank to 6.8 percent during the period from 7.4 percent in 2011.
Several other top executives left Opel last year, including its chief executive, finance chief and its head of research & development.
Before Rieck, 56, joined Opel to head sales and marketing at the beginning of July, he was president of Volkswagen's
Rieck did not respond immediately to an emailed request seeking comment.
Opel named 43-year-old Duncan Aldred, chairman and managing director of Vauxhall, GM's UK business, as interim head of sales and marketing.
Aldred, who took over at Vauxhall in January 2010, has succeeded in turning it into the country's fastest growing brand, according to the company.
"He's a rising star in the company and has a bright future ahead of him," said one Opel source.
Aldred already had a stint in Opel's Ruesselsheim headquarters in Germany, when he took on the role of sales operation director for GM Europe in April 2009.
(Reporting By Christiaan Hetzner. Editing by Jane Merriman)