Since the X5's introduction in 2000, BMW's M division has refused to tune any of the brand's SUVs, even though that crossover's basic architecture comes from the 5 Series. Now with the intro of the X5 M and X6 M at the New York auto show, BMW is giving in to competition from the Porsche Cayenne GTS and the Mercedes-Benz ML65 AMG. In more certain times, the X5/6 Ms would be surefire profit-makers.