According to my Fuelly logs, before tune my avg was 21.6mpg over 10,308 miles from April '18 to Nov '18 versus now at 22.3mpg over 3k miles. I do travel about 30% city, and on the highway I keep my cruise set to 5 to 10mph above the speed limit which I go between 70mph to 85mph here in Phoenix. I do take my corners aggressively too. Keep in mind, I do tow a 5000lb boat at least once a month for 50 miles and have been doing a lot of off road driving this past couple of months for which I do not segregate the mpg data. Summer diesel is supposed to net better fuel economy too, but I don't have any significant data on that yet.
My impressions on the tune, you can definitely feel the power increase of stage 2 over stock especially when towing particularly when accelerating. However, it was not as dramatic as a stage 2 on my MK4 Golf TDI from Kerma back in 2006 imho but maybe that's due to the DPF? Does it feel like 500lb ft of torque, yes! I have not dyno nor 0-60 time it. I love the roll of torque when merging/passing on the freeway, the Touareg just feels at home on the freeway. My only gripe is the transmission tuning which I will get done at some time. When making quick acceleration from a stop, there's a lag from when you push the accelerator pedal to when you get going which in my opinion can be dangerous when you pull out in front of traffic. When you get going though, the car pushes you back into your seat more than it did when stock and gets out of the way. I don't think it's turbo lag but instead post-fix transmission tuning as read on the clubTouareg forums. I do have the trans coded as Cayenne which slightly firms the shifts and holds the revs a little longer in drive and is more eager to downshift. Overall, Malone tuning did a great job with the tune and I would not hesitate to go with them again on another TDI.