DETROIT - General Motors Co and Volkswagen are best positioned in the largest and fastest-growing emerging markets at a time when auto sales in those countries could grow over 40 percent by 2014, a study released on Thursday said.

There were an estimated 19 million car sales on a combined basis in China, Brazil, India and Russia in 2009, accounting for 30 percent of global auto sales, estimated at 62 million units last year, the Boston Consulting Group study said.

Auto sales in those four countries would grow between 4 million and 8 million units in the next five years to reach up to 27 million units in 2014, when global auto sales are projected at 78 million to 87 million units, the study said.

The four emerging markets will challenge automakers' strategies over the past decade to push for global vehicle platforms because each country has different needs, the study said.

Auto companies cannot succeed in these markets by offering one-size-fits-all products, processes, or approaches, said Nikolaus Lang, the study's author.

China, which overtook the United States as the world's biggest market in 2009, will account for more than 60 percent of the expected sales volume in the countries, the study said.

GM and Volkswagen are the biggest players in China's auto market, where sales jumped 48 percent last year due in part to government incentives and sales tax cuts. That has provided some rare positive news for a battered industry.

They (GM and Volkswagen) really went there and established local operations, Lang said. He said latecomers would find it more challenging than before to make a profit in the increasingly competitive market.

(Reporting by Soyoung Kim. Editing by Robert MacMillan)