TrueCar.com estimates that there will be 3,345,674 used-cars sold in May, with the ratio of new to used estimated to be one-to-three. The May 2013 forecast translates into a Seasonally Adjusted Annualized Rate of 15.2 million new-car sales, up from 14.9 million in April and up from 13.9 million in May 2012.