Automotive research group Edmunds.com predicted Thursday slower growth in US auto sales next year because of economic uncertainty and a \"precarious\" global situation. Sales of light vehicles are projected to increase 4.0 percent to 15.0 million in 2013, from an estimated 14.4 million this year, Edmunds said. The likely 2013 slowdown would mark the first year of non-double-digit growth since auto sales tanked in 2009 amid the country\'s severe recession. \"Economic uncertainty at home and spillover effects from slowing economies abroad will continue to slow the pace of American economic growth, including car sales,\" Lacey Plache, Edmunds chief economist, said in a statement. Pent-up demand from consumers who put off purchases during the recession, an increasingly ageing fleet and banks flush with cash from the Federal Reserve\'s new open-ended asset-buying plan would continue to support auto sales next year, the company said. Despite the Fed\'s recent revision upwards of its growth forecast for 2013, \"the global situation remains precarious.\" Edmunds warned that the new stimulus measures from the Fed and European Central Bank, aimed at triggering growth by promoting investment and spending, may not achieve their goals. \"The potential for the economic recovery to remain sluggish in 2013 cannot be ignored and as a result, the downside risk to auto sales growth remains significant.\" Separately, a PricewaterhouseCoopers study released Thursday predicted global auto production would rise 6.5 percent to 79.6 million units this year. The European Union\'s output though would fall by 900,000 units while China\'s share would rise by 1.5 million units. World production would soar to 108 million units in 2018, with production growth in emerging markets, especially China, accounting for 83 percent of that increase, London-based PwC said.