HOUSTON — The BMW X5 is the luxury SUV with the soul of a performance sedan. That was true when it first rolled out at the turn of the century, and it remains true today. It just so happens that it maintains its all-weather, all-capable, cargo-hauling soul as well. Powered by a diesel-fueled 6 cylinder engine, it also manages a highly respectable 27 mpg, making the X5 a luxury leader in every sense.