Why you need a long-range fuel tank on your 4×4

A long-range fuel tank probably isn’t the first modification you think of, but it shouldn’t be the last.

If you’re not a touring 4X4 owner or long-distance tower then you probably never think about how far you can drive between fills of fuel. You just drop into the nearest servo whenever the gauge hits your personal definition of “empty”.  But if you are a touring 4X4 driver or long-distance tower then range, or the distance you can drive between fills, becomes really important for two reasons.

First, your fuel consumption will shoot up – towing anything large and/or heavy like a caravan dramatically increases fuel consumption. And, second, if you have a modified 4×4 then you’re very likely to have made it heavier, which means more energy needed to move it, and increased drag; for instance, taller and wider tyres with off-road tread, bull bar, driving lights, roof rack, suspension lift, snorkel…all adds drag.

The result is going to be that you might be adding 20 to 50% onto your fuel consumption figure. So let’s do a little maths based on a typical medium-sized 4×4 like a Ford Ranger or Mitsubishi Pajero:

 Typical standard ADR figureReal-world, standard vehicleModified vehicleModified vehicle with long range tank
Fuel consumption (L/100km)891313
Fuel Tank size (L)808080140
Usuable fuel (L)95%95%95%95%
Usuable capacity (L)767676133
Range (km)9508445851023
Range difference to real-world standard vehicle (km)  -44%17%

You can see that there’s a significant increase in fuel consumption and therefore range when a vehicle is modified, but a long-range tank can get that back, and then some. If you’re not sure about range, try crossing the Simpson Desert, or pulling a caravan into a headwind on the Nullabor!.

Now you could fill up a bunch of jerry cans at around 22L each, but those are difficult to carry and tiresome to empty into your tank.

You can fill up those jerries, lift them to the rack, tie them down, suffer the handling, and then reverse the process while I’ll sit here in my airconditioned vehicle watching you 🙂
If you have a ute, you can add fuel tanks or bladders – one of the tanks is water, the other is diesel – make sure you drink from the right one.

Fortunately, for owners of 4x4s, there is a much better way and it is called the long-range fuel tank; greater fuel capacity for your 4×4.

There’s two types of long-range tank; replacement and auxiliary. Replacement tanks are exactly that; remove the standard tank and in its place goes a larger version. Auxiliary tank systems leave the original tank in place, and add a second tank which is emptied into the original tank using an electric pump operated by the driver. The design of the vehicle dictates which is used; vehicles with enough space under the chassis such as utes often have replacement tanks, whereas wagons with the spare wheel underslung may  be required to relocate the spare wheel so the space can be used for an auxiliary tank.

Replacement tank on a Ranger PX for a total of 140L compared to the standard 80L. The title photo shows an auxiliary tank on a Discovery 3, which requires the spare wheel to be relocated.

Once installed, you’ll have a freedom you never knew existed. If you’re going on a weekend 4×4 trip you can fill up as you set off on Friday afternoon, and not worry about fuel again until the middle of the following week. You can drive back home after a long weekend, and pass the long queues of people without long-range tanks as they line up for a final refuel to make it home. You can sit back and watch people struggle with jerrycans. And you don’t need to worry very much about what time fuel servos are open…you’ve got plenty. 

So how can aftermarket manufacturers create more fuel capacity than the standard tank? The answer is that long range isn’t really a big criteria for many buyers, so carmakers don’t really focus on making the biggest tank they can. So the aftermarket engineers look at all the unused nooks and crannies, and expand the tank into those spaces. But tanks aren’t available for all vehicles; only the vehicles most popular for off-roading and heavy towing tend to be supported, for example all the utes, LC200, Fortuner, Pajero, Prado, and MU-X, but not SUVs such as the BMW X5, Discovery Sport and Santa Fe.

So a long-range fuel tank sounds good, but before you walk into a shop and order yourself some more fuel capacity, here are a few questions to ask:

What effect will a long-range fuel tank have on ground clearance?

Some long-range fuel tanks get their extra capacity by dropping down lower the standard, which compromises ground clearance, ramp over angle, or departure angle. More than one owner has been misadvised, or not advised of this reduction and become unhappy as a result. Now if you’re a tower you may not care (until resale time), but if you’re an off-roader, you don’t want a reduction in any clearance. Some manufacturers offer two tanks, one that doesn’t reduce clearance and one that does but has a greater capacity.

Pajero replacement tank – total of 128L for a 40L gain over the standard tank.

Does the long-range fuel tank require anything to be relocated?

In many cases wagons will need their spare wheel relocated from the underside, so you’ll either have to put it on a roofrack or fit a spare-wheel carrier. Budget for that too.

How much extra weight will the long-range fuel tank add?

The bigger tank will weigh more than the standard tank, and especially so if it is an auxiliary tank which means there’s a pump involved too, maybe adding 40-60kg of weight to the car before you add any fuel. Find out how much extra weight will be added to your vehicle…this should be a standard question for any shop but one which they may not always be able to answer.

What effect will the long-range fuel tank have on my fuel gauge?

Your standard fuel tank gauge is designed for a standard tank…and a repalcement tank may well throw it off, for example it may read well over full until you’ve used 40L or so, and read empty when there’s still 30L left. Auxiliary tanks aren’t affected by this problem, and they have their own gauges. Whatever the answer is, find out before you buy.

Auxiliary tank gauge and transfer pump switch for a Discovery 3.
Look closely…the fuel filler is split into two, one for the main and one for the auxiliary tank. Replacement tanks simply re-use the existing filler.

Are there any compatibility issues with a long-range fuel tank?

Can the fuel tank be fitted with a towbar, or your specific type of towbar? Will you need an exhaust re-routing, or maybe it doesn’t fit with your underbody protection. If your vehicle has any modifications (current or planned), then check the tank is compatible.

Does the fitting of a long-range fuel tank require any irreversible vehicle modifications?

Does the mount fitting involve cutting anything off the vehicle, or any not-easily-irreversible modifications which you may want to reverse later on?

What’s the usuable capacity of a long-range tank?

Will you really get 140L out of a 140L tank, or is it closer to 125L? Ask the question.

So what are the downsides of a long-range fuel tank?

Well, obviously it’ll cost you $$$…usually between $1500 and $2000 fitted. Then there’s the extra weight, even before you add fuel. And the tank may limit what further modifications you can make; notably exhausts and towbars. It can also restrict access for the mechanics so what was an easy job becomes a lot harder with less clearance to work with and you’ll pay the extra in hours charged.  

Why not just jerrycans?

The average long-range tank gives you around 40 to 70L of extra capacity, so that’s at least two, if not four jerrycans. You can certainly fit four jerries in any 4X4…but they not only take up a lot of space, there’s the safety aspect of carrying fuel, the smell, and you will need to stop every time you’ve used 20L and empty another jerrycan into your tank. And if you put the jerrycans on your roofrack…that’s a lot of weight up top. In contrast, the long-range tank stores fuel in places which wouldn’t otherwise be used for anything at all. Petrol can also be dangerous to decant – even the vapours can ignite. Diesel is much, much safer.

Should you buy a long-range fuel tank?

Personally, I’m a huge fan of long-range tanks and have had them on almost all my 4x4s, as I’m both a touring 4×4 owner and a tower. For example, I can tow my race car from Melbourne to Canberra without refuelling, wander around Victoria’s Deserts for a few days, or whatever else I want. I think every 4×4 tourer and tower would benefit from one, and once you’ve experienced fuelling freedom it’s hard to go back to a limited, small-capacity standard tank.

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Automotive technical journalist specialising in 4X4s, camping, racecars and towing. Has designed and run driving courses covering offroading driving, winching, track racing and towing. Enjoys most things involving wings, wheels or sails. Follow me on Facebook and YouTube if you want explanations you won't find anywhere else!