Auto sales in China are up 9% over last year through April 2014, a slower pace than last year’s 13.9% growth but still enough for Western auto manufacturers to make significant gains. Sales are expected to hit 23 million units in 2014 and 25 million in 2015, and the competition between General Motors Company (NYSE:GM), Ford Motor Company (NYSE:F), Volkswagen and others is heating up. Ford is the fastest growing brand in China General Motors Company (NYSE:GM) has been the market leader in China since 2007 and it has pushed its advantage a bit this year, but Volkswagen’s market share has…