There's no question who builds this vehicle. The X5 is immediately recognizable as a BMW. It looks like a 5 Series wagon on steroids, and is remarkably close in overall size. From the kidney-shaped grille to the tailgates, the curvy X5 is all BMW. The slope of the tailgate looks almost identical to that of the 5 Series wagon. The major difference is that the X5 is 10 inches taller than the 5 Series wagon. This increased ride height is the key element of making this vehicle more like a sport-utility. Big-diameter wheels with low-profile tires that lend an aggressive appearance.BMW's X5 is called a light-duty truck by the government. Most truck-based SUVs, including the Mercedes-Benz M-Class, are built with the body bolted onto a frame. The X5, however, uses a monocoque body shell like that of a regular sedan. This unit-body construction provides a much stiffer body shell, which improves handling, reduces noise and allows better fit and finish. The X5 is not the first monocoque SUV; the Lexus RX 300 and the Jeep Grand Cherokee follow the same design concept.