Improving your 4WD’s Fuel Economy

Let’s face it; four wheel drives aren’t exactly the most fuel efficient cars, but the places they can take you more than makes up for the extra cost. When you are parked up on one of the best beaches in the world with no one in sight, the hole burning in your pocket is soon forgotten! Regardless of what you drive, there are a number of things that you can do to improve your fuel economy, which I will go through below.

Working out your fuel economy

To start off with, how many of you actually know what your four wheel drives fuel economy is? In Australia, most people refer to it in litres of fuel used per 100 km. To work this out, simply divide the fuel used by the number of kilometres done, and then multiply it by 100.

For example, if you filled up with 78.5 litres of diesel, and you did 502km, just divide 78.5 by 502 (0.15637). Then, multiply it by 100 and you get 15.637 litres of fuel used per hundred km. I make it a habit of working out the economy as I walk into the fuel station to pay for it, so I can keep an eye on how the vehicle is performing. Be sure to factor in larger diameter tyres when you are working this out!

  • Clean your air filter

Your air filter takes 5 minutes to clean, and can result in huge improvements to your fuel economy. Simply unclip the filter housing, remove the filter and inspect it. Give the filter a few taps against the tyre, and see how much dust comes out. I usually keep tapping it until the dust stops coming out. It only takes a few minutes behind another vehicle on a dusty road to warrant cleaning your air filter, and I try to do it at least a couple of times on each camping trip. By installing a snorkel, you will find the air filter needs cleaning much less often too, as it sucks clean air in.

  • Tyre Pressures in a 4WD

    What pressure are your tyres?

    Check your tyre pressures

The more air you have in your tyres, the less rolling resistance they have and the greater fuel economy you will get. However, don’t go and pump your tyres up to 60PSI, or they won’t handle safely on the road and you will wear them out very quickly. The compromise is to find the pressure that evenly wears your tyres, whilst not working the vehicle too hard. The bigger the tyre, the less air required to keep the vehicle rolling. If you haven’ heard of the 4PSI rule, it’s a good one to learn.

Particularly on sand, if you don’t let your tyres down you will make your 4WD work considerably harder and it will use a lot more fuel. Adjust your tyre pressures for the terrain you are driving on and you will get better economy, more traction, less damage to the tracks and to your 4WD and less chance of something going sideways.

  • Get a wheel alignment

If your wheels aren’t properly aligned, they can be working against each other. If the front wheels are not parallel with each other, one is trying to go one way and the other a different direction. This guarantees you are going to use more fuel than necessary; so make sure you get it checked out from time to time.

  • Snorkel on a 4WD

    A snorkel has a number of benefits

    Allow the vehicle to breath better with a snorkel

A snorkel helps to feed the engine with clean air, and will usually result in a more economical 4WD. It also makes it safer to do water crossings, and minimizes the dust that gets sucked into your air filter.

  • Restricted 4WD exhaust

    Factory exhausts often restrict the airflow

    Install an exhaust that allows better flow

Most four wheel drives come with exhausts that restrict the flow of the engine. However, if you go too big on the exhaust size, you will find the vehicle uses more fuel as there is no back pressure. For the 80 series turbo diesel, a 3” exhaust is the perfect combination.

  • Service your vehicle

If your vehicle is overdue for a service, don’t put it off any longer. It’s costing you in the economy, and likely reducing the life span of various components on the 4WD. At the very least, replace your fluids (engine, transmission/gearbox/transfer case) and diffs!), and check the brakes work properly! Oil turns to sludge over time and will make the engine work harder, thus using more fuel.

  • Quality fuel goes a long way

    Pay attention to where you fill up

    Fill up with quality fuel

Some people are going to disagree with me here, but every time I fill up at one of the lesser known fuel stations, I get worse economy than if I fill up at a Shell, Caltex or BP. The fuel qualities must vary and can have a big impact on your economy.

  • Drive more economically

If you find yourself accelerating hard and braking often, your fuel economy could be drastically improved. Whilst hearing the rumble of a nice 4WD engine with your foot flat on the floor is appealing, it’s eating a big hole in your wallet! Take your foot off the loud pedal earlier when approaching intersections, and allow the vehicle to engine brake or roll to lose momentum rather than hitting the brakes hard at the last minute. You will find that this will preserve your vehicle better too; the brake pads will need replacing less often, the tyres will last longer and the wear and tear on the vehicle overall will be lessened.

  • Remove anything out of your vehicle that isn’t needed

If you only use your roof rack once a year, pull it off for the rest of the time. You will save about 10% in fuel. The same applies for big tyres, camping gear and excessive tools in your car. If they aren’t needed, take them off and you will be very surprised at how much further a tank of fuel will go.

  • Check your sensors are working properly

Modern 4WD’s have a number of sensors that impact on your economy. These include MAF and O2 (oxygen) sensors. If they are faulty or damaged, they can have a drastic impact on the amount of fuel that you use!

  • Fuel increase via bigger tyres

    Bigger tyres will usually cost you more fuel

    Run the correct size tyres (or re-gear the 4WD)

Have a look at the nameplate on your 4WD to check that it is running the correct size tyres. If you (or the previous owner) has gone up a tyre size, you will find the fuel economy will generally decrease. This is because the vehicle has to work harder to turn the tyres. Even though your RPM for any given speed has dropped, the engine will have to work harder as you have effectively re-geared the vehicle. This is always a compromise, and you can look at re-gearing the vehicle to suit the larger tyres as an alternative.

  •  Engine modifications

A common modification is to install a turbo, or an intercooler (if you already have a turbo). These will provide the vehicle with more power, and if driven in a similar manner should also provide better fuel economy.

I’d love to hear what your fuel economy is – post up your vehicle, year, engine size and fuel type too!

My 1990 80 Series Land Cruiser with the 1HDT 12 valve factory turbo diesel engine gets around 14 – 17L/100km, fully loaded with a substantial number of modifications and a fair bit of 4WDing thrown into the mix.

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