Your vehicle’s official fuel consumption figure is irrelevant the moment you hitch up a caravan. A ute rated at 8L/100km on the highway will consume 14 to 18L/100km when towing. A large 4WD rated at 10L/100km will consume 16 to 22L/100km. The additional weight, air resistance, and mechanical stress of dragging a large box through the air at highway speed transforms your vehicle’s fuel economy dramatically. Understanding what’s realistic for your setup, and knowing which variables you can influence, is the difference between an accurate fuel budget and one that runs out halfway through the Nullarbor.
Towing adds 30 to 60% to your unladen fuel consumption. Know what yours is before you budget for the trip.
What Towing Does To Your Fuel Economy
Towing increases fuel consumption through three mechanisms, and understanding them explains why different setups vary so much.
Weight. Your engine has to accelerate and move the combined mass of the vehicle and caravan. A 2,500kg caravan behind a 2,800kg vehicle means the engine is moving 5,300kg instead of 2,800kg. That’s roughly double the mass, which increases fuel consumption on hills, in stop-start situations, and during acceleration. Weight affects consumption most on hilly or undulating terrain.
Aerodynamic drag. A caravan is essentially a large, flat-fronted box being pushed through the air. At highway speed, aerodynamic drag is the dominant factor in fuel consumption. Drag increases with the square of speed: doubling your speed quadruples the drag. This is why the difference between 95km/h and 110km/h has such a massive impact on consumption.
Rolling resistance. More tyres on the road (4 vehicle tyres + 2 to 4 caravan tyres) means more rolling resistance. Tyre pressure, tyre quality, road surface, and alignment all affect this. It’s a smaller factor than weight and drag but still meaningful.
The combined effect: expect your unladen fuel consumption to increase by 30 to 60% when towing. For most setups, 40 to 50% is typical.
Realistic Consumption By Setup
| Setup | Typical Consumption | Cost per 100km at $2.00/L |
|---|---|---|
| Small ute + pop-top/light van (under 1,800kg) | 12–16L/100km | $24–$32 |
| Mid-size SUV/ute + mid-range van (1,800–2,500kg) | 15–19L/100km | $30–$38 |
| Large 4WD + heavy van (2,500–3,500kg) | 18–22L/100km | $36–$44 |
| Large 4WD + big rig (3,000kg+) | 20–25L/100km | $40–$50 |
These are highway figures on flat, sealed roads at 90 to 100km/h. Add 10 to 20% for hilly terrain, 15 to 30% for unsealed roads, and 10 to 20% for consistent headwinds. Your actual consumption on a trip that includes all terrain types will average higher than flat-highway figures.
The Factors You Can Control
Speed. The single most impactful variable. Aerodynamic drag increases exponentially, so the fuel penalty for speed is disproportionate. At 95km/h versus 110km/h, most setups save 10 to 15% on consumption. Over 30,000km at 18L/100km, that’s 540 to 810 litres saved, or $1,080 to $1,620. The trip takes slightly longer, but at Big Lap distances, the time difference per day is 15 to 30 minutes. A small price for $1,000+ in savings.
Tyre pressures. Underinflated tyres increase rolling resistance and consumption. Overinflated tyres reduce grip and tyre life. Check and adjust to the manufacturer’s recommended towing pressures (not unladen pressures) before every drive. On unsealed roads, reduce pressures as recommended for the surface, then re-inflate for bitumen.
Weight reduction. Every kilogram you carry costs fuel. Carry water in your tanks only when you need full tanks (not between towns with reliable water). Empty grey and black water before travel. Don’t carry items “just in case” that you haven’t used in months. A 100kg weight reduction on a 5,000kg combination improves consumption by roughly 1 to 2%.
Driving style. Smooth, anticipatory driving saves fuel. Accelerate gently, maintain momentum on hills (let speed drop slightly on climbs rather than flooring it), use cruise control on flat highways, and avoid unnecessary braking. Aggressive driving (hard acceleration, late braking, constant speed changes) increases consumption by 10 to 15%.
Vehicle maintenance. A clean air filter, fresh oil, properly functioning cooling system, and a well-maintained engine all contribute to optimal efficiency. A neglected engine can use 5 to 10% more fuel than a maintained one. Pre-departure servicing pays for itself in fuel savings.
95km/h instead of 110. It’s the least exciting fuel-saving tip and the most effective one by a significant margin.
The Factors You Can’t
Terrain. You can’t flatten the mountains. Hilly routes consume more fuel, period. You can choose flatter route alternatives where they exist, but much of Australia’s coastline involves hills and ranges. Budget for it rather than pretending it won’t happen.
Wind. Headwinds of 20 to 30km/h increase consumption by 10 to 20%. Prevailing winds in Australia generally blow from the south-west, which affects west-to-east travel along the southern coast and south-to-north travel up the western coast. You can check forecasts and delay travel on particularly windy days, but you can’t eliminate the impact.
Your setup’s aerodynamics. A caravan is inherently unaerodynamic. Some vans are worse than others (taller, wider, flat-fronted), but short of buying a different van, you can’t change this. Roof-mounted accessories (kayak racks, storage boxes) on the vehicle increase drag further. Remove anything that’s not needed.
Fuel quality. Remote area fuel can be lower quality or older, which may slightly reduce efficiency. Not a significant factor but worth noting if you notice consumption spikes in certain areas.
Tracking Your Real Consumption
Track from the first fill. At every fuel stop, note the odometer reading and litres filled. Calculate consumption: (litres ÷ km driven) × 100 = L/100km. A simple spreadsheet or even a notebook works. After 5 to 10 fills, you’ll have a reliable average for your specific setup.
Why it matters: Your actual consumption determines your range (critical for remote legs), your fuel budget (critical for the whole trip), and whether any changes you make (speed, weight, maintenance) are actually working. Without tracking, you’re guessing.
Use the trip computer cautiously. Most modern vehicles have a trip computer that displays real-time and average consumption. These are indicative but not always accurate, particularly when towing. Cross-check against your manual calculations. If they differ by more than 5%, trust the manual calculation.
A sudden increase in fuel consumption (more than 10% above your established average) can indicate a mechanical issue: dirty air filter, dragging brakes, tyre problem, or engine fault. Investigate before assuming it’s just terrain or wind. Early detection prevents expensive repairs.
- Towing increases fuel consumption by 30 to 60% over unladen driving. Expect 14 to 22L/100km for most Big Lap setups.
- Speed is the biggest controllable factor. Dropping from 110 to 95km/h saves 10 to 15%, worth $1,000 to $1,600 over 30,000km.
- Correct tyre pressures, smooth driving, weight reduction, and vehicle maintenance each save 1 to 5%. Combined they’re significant.
- Track real consumption from your first fill. Your actual numbers determine your range, your budget, and whether changes you make are working.
- A sudden consumption spike (10%+ above average) may indicate a mechanical issue. Investigate early.
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