Vehicle Overview, Since its debut as a 1999 model, the RX 300 sport utility vehicle has become the best-selling Lexus model in the Japanese automaker’s lineup, handily outperforming the company’s passenger cars. , , Issued by Toyota’s luxury division, the RX 300 is related to the Toyota Highlander, but the connection isn’t obvious because the Highlander has different styling touches and fewer standard features. Considered a crossover model, the RX 300 is built on a passenger-car platform.