Shares of Ford Motor Company are up 30% so far this year, and booming sales of models like this F-150 pickup are a big reason why. Photo credit: Ford Motor Co.

Auto sales in the U.S. took a sharp hit during the recession, but they've since come back strong. New-vehicle sales are up over 8% so far in 2013, following on the big gains made in 2012. Those strong sales have helped shares of automakers like Ford (NYSE:F) and General Motors (NYSE:GM) post gains that have outperformed the market.

But this all comes as other economic indicators, like unemployment, remain sluggish. What's driving these sales? One answer is "easy credit" -- and that raises another question: Is this another bubble that's set to pop?

In this video, Motley Fool contributor John Rosevear takes a hard look at that question -- and at the state of new-car financing, where loans have become very easy to get, and where subprime lending is making a big comeback.

Fool contributor John Rosevear owns shares of Ford and General Motors. You can connect with him on Twitter at @jrosevearThe Motley Fool recommends Ford and General Motors. The Motley Fool owns shares of Ford. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.