Two days, two six-cylinder German SUVs. Compared to the VW Touareg 3.6, the BMW X5 3.0 is quicker, much harsher riding (on 19-inch run-flats), and has heavier steering. It's also more than $6000 pricier. All of which is pretty much what you'd expect. The only surprise? The BMW gets much better gas mileage: 17/23 versus 14/20, according to the EPA.