Mihnea Stanciu/FlickrWall Street is starting to worry about the auto loan market. Fitch, Moody's, Morgan Stanley, Mizuho and Evercore ISI have all published research on the market in the past few days, and there's a recurring theme: It's not looking good. There could be wide-ranging consequences, with automakers, the economy, consumers and one corner of the bond market all potentially taking a hit.