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With the current impacts on petrol and diesel prices, for many of us planning a road trip these Easter holidays, there’s a lot more to consider than just what to load into our cars and caravans. For plenty of people towing caravans, where fuel consumption could be close to 20L/100km, the hip pocket hit could be big one.
Whether fuel prices are up or down, we’re all looking for ways to avoid spending extra money when caravanning, while still enjoying some time away. So, what can be done? And how can we save money while towing, not just when fuel costs are high, but all the time?
Maybe this doesn’t need to be said, but towing at a slower speed can have a marked impact on fuel economy. There’s some solid data and (dare we say it) maths behind it. A big part of that is thanks to reduced air resistance.
When we tow our big, square aero-undynamic homes on wheels, they must push a lot of air out of the way. Air resistance increases exponentially with speed. In a real-world example, your combination’s air resistance quadruples when you double your speed. If air resistance is around 100 Newtons at 50km/h, it will be around 400 Newtons at 100km/h.
There’s not a lot of data specifically on caravans, but anecdotally, at highway speeds, air resistance accounts for around 50 per cent of fuel consumption.
Clearly, none of us wants to head up the highway at 50km/h, so slowing down that much is probably unreasonable. But, even at 85km/h, we get about a 27 per cent reduction in air resistance.
Many modern cars have a live fuel usage gauge or display on the dash. If your car does too, you’ve probably noticed that during hard acceleration, fuel economy decreases significantly. By adjusting your driving style to accelerate more gently (but not too gently, as that tips the scales the other way), you can help reduce fuel consumption throughout the trip. Likewise, allowing the car and caravan to coast more slowly to a stop, or by braking earlier and more gently when you can, you don’t waste the energy you’ve just used getting yourself up to speed. In general, the less often you change your speed, the better your fuel economy will be.
While slowing down has the greatest effect on drag, other factors can also help. Anything that reduces your vehicle's aerodynamics increases fuel consumption. Roof racks stacked with odd-shaped items, bike racks, light bars, dirt and mud, or even shortening the gap between the back of your vehicle and the front of a caravan (for example, by using a canopy on your ute, or a shorter hitch if that’s possible). These might only be marginal savings, but it all adds up.
Trailer height also plays a big part. Clearly, we can’t easily lop the top off our caravans, but many people have adjustable air suspension, so running that at its lowest height can really help. For those of us with camper trailers or other low trailers, reduce the amount of gear carried on top that could create drag.
These days, we tend to bring quite a lot with us when we camp. If you want to save fuel, shedding some kilos for the long drive will help. If you can, leave the van with empty water tanks and fill up at camp (if possible) or somewhere closer if the community you’re visiting doesn’t have water shortages. Consider buying heavier groceries at your destination or just shedding some of the heavy luxuries you may not need. Is that generator and fuel you always carry, just in case, necessary for your trip to Busselton? Are two spare tyres on your four-wheel drive essential for a trip to Jurien Bay? Two gas bottles for a long weekend trip? Cast iron campfire cookware for a caravan park that doesn’t allow fires? It all adds up.
Sailors will understand the concept of apparent wind, but we don’t often need to think about it in an SUV. Apparent wind is the wind you actually feel when moving. For example, on a windless day, if you open the window of your car driving at 50km/h, the apparent wind on your face is 50km/h. If, driving at the same speed, the wind is blowing from directly behind you at 20km/h, then the apparent wind is 30km/h. Likewise, if you are driving at 100km/h into the Freo Doctor, the apparent wind speed could reach 150km/h. Going back to our calculations on air resistance, there is a significant exponential increase in drag, which will have an oversized effect on fuel economy.
Of course, we won’t always be able to avoid driving into the wind, but we can minimise it. Up and down the WA coast, winds are often strongest in the afternoons, and predominantly from the southwest. If you can’t drive with it, consider starting earlier in the mornings when the wind is typically lighter.
Using the FuelWatch website will help you find the best prices to fill up before you leave. FuelWatch lists current fuel prices across WA, and from 3pm each day, also lists prices for the following day. It also has service station contact details, so you can call ahead if you are worried about supply in more remote areas.
When your engine is running at its best, and all the downstream components are in good shape, you’ll get the best fuel economy. Oil that doesn’t lubricate properly, bearings that don’t roll smoothly and exhaust that doesn’t exhaust efficiently all contribute to higher fuel consumption, so keep your services up to date and you’ll get further on each tank.
Tyre pressure can have a notable effect on fuel economy (as well as vehicle and braking performance), so regularly checking and topping them up is important. Statistics show that a significant number of drivers get around on underinflated tyres. All vehicles, as well as trailers and caravans, have recommended tyre pressures for certain loads. Filling yours to the right pressure could improve fuel economy by as much as 5 per cent. Get yourself a decent tyre gauge and check it regularly while the tyres are cool.
You could of course always consider just packing a tent for your road trip this time around. It might be a great opportunity to pare things back a little and camp more simply. Towing a box trailer or just fitting all your camping gear in your car could save you hundreds of dollars in fuel, while still getting you out of the city these holidays.
No doubt your social feeds are chockers full of ads and influencers spruiking the latest fuel saving additive or gizmo that they can’t believe they drove without. But do they work? It’s probably wise to approach many of these things with a healthy level of scepticism. Certainly, there are engine modifications you can make to improve fuel efficiency, power, or torque. All come with compromises. Get more than one opinion before committing to anything permanent or expensive.
