The used car market was very popular for a while, and then people started buying new cars more often than used ones. The economy was booming, people had good jobs, and they wanted to have some prestige and feel good about themselves, so they went out and exercised their ability to get credit by purchasing new cars. However, that's not always the best thing in the world to do, and some of these people found that they couldn't make their payments. Just because someone will give you credit to buy something doesn't necessarily mean that you can afford whatever it is that you're buying. That's an important thing to keep in mind so matter what kind of credit you might be considering. Now the economy has changed, though, and although there seem to be a few signs of recovery there are still many reasons to think that a recession is going to hang around for a while longer. This might be bad for some people, but it's great news for those who are trying to sell used cars. People can't afford new ones as easily as they used to be able to. Even people with pretty good credit are having trouble getting loans for new cars because the credit market is so tight, so they have to buy used ones - and there are some great deals out there.
Some people don't like to buy used cars, but there is a huge difference between a fifteen-year old 'clunker' and a car that's five years old and has been well cared for. People will ultimately have to buy what they can afford, so some of those older cars will get sold as well as the newer ones. Most used cars being sold today are just a few years old. They've had one or maybe two owners, and they've been treated really well. People like them because they still drive like new - and often look new, too - but they don't cost as much. All of the depreciation that happens when you drive that brand new car off the lot has already been taken by someone else, so they can get a great car at a lower cost. That realization, coupled with a lack of credit and the overall cost of buying a new car, makes a lot more people interested in purchasing a used car that they can get a great deal on instead.