According to a recent survey of analysts by Bloomberg News, sales of new vehicles increased in June to the fastest pace since December 2007. U.S. light vehicle sales are estimated to have increased 7.1% to 1.38 million vehicles last month. This increase keeps the U.S. on pace for its best annual automotive sales in six years. Analysts estimate that annual sales may be as high as 15.6 million vehicles at the end of 2013, up from 14.4 million in 2012.While volatility in stock markets and mortgage rates will test the confidence of consumers to keep buying new vehicles, pent-up demand and low interest rates, which have been the fundamental reasons for the increase in sales over the past year, remain.Easier Credit Should Keep Auto Sales on TrackEasier credit, even for riskier subprime borrowers, has fueled what should be the U.S. auto industry’s best year since 2007, but there is little danger that consumers are overextending themselves, according to data from Experian Automotive, a credit-monitoring firm. While credit is getting easier to obtain, more buyers are financing their new vehicles over longer terms, between five and seven years. That trend could present problems for those consumers if they want to buy again in three or four years because they will owe more than their vehicles are worth.