I owned a 2006 V10 TDI Treg and a 2007 V8 FSI Q7. Things to consider: do you need the third row seat? What sort of climate is this geared towards? Any offroading? The first two generations (first then facelift really) through 2010 of touaregs had significantly more capable 4x4 with options for locking diffs etc, those early touaregs were absolute tanks, try as I might I never got that thing stuck in several feet of snow. If you're looking at newer ones I would still vote touareg, the Q7 is long overdue for an update and these new touaregs seem to show promise for build quality and reliability based on what I read on ClubTouareg, where I'm still a member. If the extra space is crucial obviously the favor tips towards the Q7 but as a "big" SUV it's really not that big, the third row is borderline useless and even with all those seats folded it doesn't offer that much more space than a touareg. The Diesel engines are the way to go for sure, the old V8 was abysmal on gas and still not very quick so go with the TDI, no brainer.
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