I've found it's more a case of how many miles are done in 4wd low and not so much as "on the trail". Definitely suck a lot of gas when doing 4wd low. Airing down also hurts gas mileage. Fortunately, New Mexico's sections of the CDT are fairly easy, I did most of the BDR in 2wd or at most, 4wd high and sections of that overlapped with the CDT so feel like they are comparable. That being said, I do carry an extra 7 gallons just in case. While I didn't need them, it definitely can get sketchy with the distances between towns with working gas stations out there. I also think it's just important to keep gas levels in mind and not get picky on where you stop to get gas (shopping for a lower price, etc.) or consider small detours to go get gas when needed.
