It truly confuses my on why people worry about gas milage on 4x4 campers, they are very heavy and use a lot of fuel.. I'll be completely honest, if gas milage is an issue get a tacoma, and an alaskan camper. Don't expect any thing better than +/- 15mpg on 90's and 00's E-series campers.. The 7.3L is absolutely amazing, 6.0L is good if bulletproofed, so is the V10 gasser- but they are fuel hogs. Having 3 easy low maintenance 500,000+ mile engines is the plus, and that should be the deciding factor not MPG's.. Delica 4x4's are also a good option if money is a huge factor.