PORTLAND, Ore. ( TheStreet) -- Just because a car is used doesn't mean it's a great deal.Depending on where you live, the price of a used car on a dealer's lot or even in a listing on Craigslist can be considerably more than what someone on the other side of the country is paying. Supply, demand and the general economy of the surrounding area mean there might be better deals just a few towns away or across the state border. "Prices can vary substantially from city to city, and depending on where you live, it may pay to look beyond your ZIP code to find greater savings," said Langley Steinert, founder and chief executive of used car pricing site CarGurus. New car sales jumped 13.4% last year as Americans made their way back onto dealer lots. Still, they did so reluctantly; automotive data service revealed last year that the average age of cars and light trucks on U.S. roads is roughly 11 years. That's up from 8.9 years a decade ago and 9.8 as recently as 2007. New car sales slumped during the 2008 and 2009 recession years as U.S. drivers squeezed as much mileage out of their old cars as possible. By holding onto their used cars, consumers threw off a very delicate balance and decimated used car supplies. According to Manheim Consulting's Used Vehicle Value Index, used car prices actually fell 0.8% last year, but jolted up 1.2% in December as Superstorm Sandy reduced an already small supply. Dwindling new car inventory and used car lots already emptied of 2- and 3-year-old vehicles are keeping prices high as sales rose 5% in 2012 and more than 10% from 2010. That makes even the most utilitarian and undesirable used vehicles a popular commodity these days. Manheim found that owners looking to sell their old Toyota ( TM) Camry, Honda ( HMC) Accord or Ford ( F) Fusion will make an average 2% more on the deal than they would have last December Even used pickups and vans have benefited, with demand accelerating 2.6% and 0.2% respectively within the past year.