The economic slowdown in China has hit GM sales for the first half of the year. General Motors saw growth in its biggest market outpaced by U.S. domestic sales. Local Chinese competitors have also put the brakes on GM auto sales by flooding the SUV market with cheaper options. For the first 6 months of 2015 GM sold 1.72 million vehicles in China. Overall sales growth rate was 4.4. percent, up just 0.4 percent from last year's numbers. By contrast, the U.S. domestic market offered a bright spot for the autos retailer, with a growth rate of 4.5 percent. The American car market experienced surging car sales as consumers cashed in on cheaper gas prices and low interest rates.