Elevated gas prices have helped to drive a surge in used compact car prices, according to a data analysis by Edmunds.com, the premier online resource for automotive information. Edmunds.com’s data reveal that consumers paid about 10 percent more for used three-year-old compact cars in July than in January. By comparison, prices for this segment rose just 1.6 percent over the same period in 2010, and 1.1 percent in 2008, the last time gas prices crept over $4/gallon.