Just got a 2012 Q7. Great vehicle. Excellent for trips. Love it. Too bad it is the wife's car! I get to borrow it to pull the trailer. Big improvement over the Tahoe. Question: I don't seem to be able to get a complete answer from the dealer about whether the electronic brake controller is built in and how well does it work? Has any tried this? Does it just work? Is an additional controller box needed? If it is built in how do you adjust the braking bias? (My auxilary boxes always had a dial to adjust it) Also I am curious what fuel mileage anyone gets towing a 4000 pound enclosed car carrier. Without the trailer we get 30 highway at 60-65, 27 at 70-75, 21 around town. Idling for extended periods seem to use fuel more than driving it.