The two common and obvious fuel options when choosing what expedition vehicle to purchase and set up are gas and diesel. At first thought you may not realize quite how important this selection is, and it can be the determining factor in which truck you select.
The first point to consider is availability. Where do you plan to use your overland vehicle? Many third world countries, especially Africa have unreliable supplies of petrol. In addition to the availability problem is the quality that is delivered once you find it. If running an older model vehicle this might not matter as much. If you plan to set off acoss the Sahara in your brand new Range Rover V8 you might be in for a very unpleasant surprise. I can tell you when I crossed Western Africa in my 1965 Land Rover with adequate jerry cans finding petrol was not a huge issue. The quality often times was not so good, but after accidentally being topped off with diesel, I also found that the old engine would run on just about anything.
If your destination is North America you will certainly find diesel not always as readily available as petrol.
As far as the engine goes the advantage of diesel is torque, usually lots of it, this is especially good at lower RPM’s while off the beaten track. The negative that often comes with torque is lack of speed. Usually diesel trucks will not be setting any land speed records. Keep this in mind. If you are going to spend a ton of time on fast paved roads you probably want to have the ability to cruise at speeds in the mid 60MPH range.
Diesel engines often have less things to go wrong with them and most are extremely reliable. Petrol powered ones tend to be more tempermental. However, if a diesel engine does have a component fail it is usually harder to find and more critical to the forward progress. That is, I have found many ways to jerry rig a petrol engine and at least have been able to cobble something together to get to camp.
Cost also must be considered. Both the cost of the fuel and the cost of the engine and thus the vehicle. Generally diesel is cheaper to run, especially since it tends to get better economy. Gasoline engines are usually cheaper thus the vehicle is often more affordable as well.
I made the decision recently to switch from gasoline power in a Land Rover 101 forward control to the diesel power of a Mercedes Unimog. Although fuel was only one factor, it was one of the main objectives for the switch. The factors I primarily was concerned with were; fuel economy (6 vs 13MPG), ignition system, fuel availability in South and Central America and with fast axles in the Mog I can still acheive a reasonable cruising speed on the highway.
The bottom line. Like most things, it depends. Consider where you will be traveling, your budget, your level of repair skills and what vehicles are available in each fuel category.
Finally, as a shameless plug. The picture above contains images of Drive The Globe’s Gas Only & Diesel Only decals. We design and manufacture these for off road and overland enthusiasts to place on their vehicles and jerry cans to avoid having the wrong fuel put into your truck at the worst possible time. Take it from me, I have been there and done that. They are available at our SHOP.