Yes, the increase in U.S. car sales is an indication that the United States is finally starting to experience a full recovery. Although the country has not fully recovered yet, more jobs have been created and more people are getting back to work. The pent-up demand to replace old cars with new ones is one indication that the country is starting to get back on track.
A car can last for many years before needing to be replaced, so I think the purchase of a new car is definitely a discretionary purchase. Someone usually only makes such a purchase when one is very confident that one has excess money to spare, or that one can afford the loan over several years. The people buying the cars must feel the recovery is happening, so must be a good indicator of feelings at street level.
Any time consumers begin making purchases again, especially large purchases, it is a great sign that the economy is improving. I am not sure we are quite at a full recovery stage yet, but car sales combined with increasing home prices leads me to believe that the U.S. is getting there in terms of recovery.
No, the recent revitalization of U.S. Car sales does not hint at a full recovery, because the market had to bottom out at some point. The market for car sales couldn't get any lower. At some point, people's cars were going to break, and they would have needed new ones whether they could afford it or not.