Since lows in 2010, auto sales have surged, and have been a bright spot in the U.S. economy. But how much of the surge has been catch up from the sharp drop that began in 2008? More importantly, can the surge continue now that the auto-buying levels of the 2004-07 era have been reached? With oil petering out, home sales flat, exports facing tougher competition from a stronger dollar, and a possible stall in auto-sales, where will new growth come from in the U.S.?