The critical acclaim of its newest sedan, the Cadillac CTS, prompted GM to spawn both wagon and coupe derivatives off the platform. If Mark McNabb, the president of the Cadillac-Hummer-Saab channel gets his way, Cadillac will get more models based on that scenario."Look at a CTS and I think you can start understanding where we are going. Look at a CTS [sedan], CTS wagon, CTS coupe - obviously, derivatives off a platform make a lot of sense from a financial perspective," McNabb said at the 2009 Chicago Auto Show.Cadillac's plan mimics the business model of one of Europe's biggest luxury players, Mercedes-Benz, which offers several niche models based on similar platforms. BMW has been following the trend as well, debuting an X6 "sports activity...