RALEIGH, N.C. — For almost two decades, the Lexus RX has been the benchmark for luxury midsized crossovers and SUVs. The yard marks are wide, but you’re going to shell out anywhere between $45,000 and $70,000 to purchase one. The competitive set includes the cream of the crop: Audi Q5, Land Rover Discovery Sport, Mercedes-Benz GLA, and a few others. Price notwithstanding, this segment is growing so fast, it seems that within five years, Americans will be issued one with their learning permits.