So, I just added the ACES IV to my S6 for the trip to and from Monterey from the Bay area, about 90 miles each way, and got about an additional MPG even on the first tank with it. And Dave, we are also adding ACES Diesel formula into our Cayenne diesel, which I would guess you'll be doing as well. I had used it religiously in my original RS6, as well as Brian's oil, and at over 135K miles the engine was pristine, per Mr. Hall. Posting this really for those relatively new to the forum, and of course I expect some haters to call this stuff snake oil. Snakes are lubricious. So is ACES!