CarMax (NYSE: KMX) stock is trading near its highs of the day, up 14.2% as of 2:45 p.m. EDT, after the used car specialist reported fiscal Q1 2018 earnings results this morning.CarMax earned $1.33 per share in Q1 on sales of $4.79 billion, beating analyst expectations for both sales and earnings.CarMax sells a whole lot of cars -- a lot of them wholesale.