Hi guys, thanks for all of your responses! I actually have a dual-fuel Tahoe with 21 gge!! The std 2 tank add plus 3 additional giving me over 400 mile cng range if I get goof fuel economy! I am having the best time planning this trip. Everyone is so helpful and passionate about CNG. I have been spending a lot of time on the phone with stations to ensure I can refuel, and everyone has a great story. Please visit my blog and make comments, most of the site visitors aren't as well-versed in all of this as you all so your knowledge will be very helpful! www dot greenamericanroadtrip dot com