With the roof rack as shown with gas cans on top I get just under 16mpg, just over 16 without the rack at 60-65 (secondary hiways), 528 mi.
Strictly 2wd dirt roads 13-14mpg. 429+mi
10-11 mpg on dirt mixed low range and two wheel 10 mph type roads and about 7 (or less)mpg if most of the time is in low range. 330+ mi.
33 gal tank.
I put a forty gallon expansion tank in my 07 f150 that makes a total of 66 gallons without having to fill up (including from jerry cans).At 13 mpg I can make it 858 miles. If I do the 4bt swap as I would like probably well over 1000.
Back in the day with my 1970 FJ-55/Chevy 307 V8/Hone Over Drive/ i could go a long way. With what? It's been 40 yrs. since I owned the FJ, but it had a replacement fuel tank with a 53 gallon capacity. On the tailgate were two 5 gallon jeep cans. On the roof or on the Con Fer Toyota jeep trailer were four more 5 gallon cans. So, what's that, 83 gallons? The pre-smog Chevy V8/Land Cruiser got 14 mpg on the highway at 55 mph in overdrive, and dropped to about 8 mpg off-road. Once going across Laguna Chapala in Baja, we stopped at the Rancho for lunch. The proprietor asked if we wanted gas. I said no, we have plenty. He said everyone who passes through here buys gas from him. This was on a trip where we gassed up in Ensenada, drove half way down the peninsula, drove east across the gap in the mountains to the gulf coast and drove north gassing up in San Felipe. It was about 550 miles, mostly on dirt and sandy tracks.
2005 Dodge 2500 4x4 Hemi, 4.56 gears, 37/12.5R17 BFG AT tires, with all my kit for camping.
130L (35 gal) main tank
205L (55 gal) aux tank
On highway about 1500 km (940mi) with 1/2 tank (70L) left for reserve.
Back roads about 1100 km (685mi) with 1/2 tank left for reserve
Now that I am running heavier 38/15.5R18 Toyo MT's I imagine I'll lose some distance.
1998 TJ four cylinder 33" tires/4.88 gears/3.5" lift/etc. Figure 15 mpg pulling a small trailer. So 18 gallons in the tank, five gallon Jerry can on the swing-away rear bumper, 12 additional gallons on the trailer = 35 gallons. 35 x 15 = 525 miles. I don't really want to test it out though.
1978 Mercedes 240D.
Main tank 18 gallons.
Aux. fuel tank in trunk, 15 gallons. 33 gallon total.
I have gone 928 without refueling, reserve light not yet on.
I think I can squeeze 1000 out of it on the right roads.
With a usable 350lt in the two tanks, we can get on average 1600km on dirt roads, 2000km on tar roads, and 1200km off road ( Canning stock route type of off road ) We can also carry another 100lt in jerry cans down in various storage compartments ( if we move stuff around) and if desperate, another 100lt on the roof rack to give us another 500-1000km kilometers if we need to.