Fuel is the single biggest variable cost in van life. A Transit Custom that does 35mpg vs one that does 30mpg saves you £500-800 per year in diesel. Tracking your fuel economy lets you spot problems early, adjust your driving, and save money.
This guide covers how to track fuel economy accurately, what good numbers look like for different vans, and how to improve yours.
Why Bother Tracking?
Most van lifers don't track fuel economy. They fill up, pay, and forget. Over a year, the difference between an efficient and inefficient van is significant:
| Van | Average MPG | Annual Fuel Cost (12k miles, £1.55/L) |
|---|---|---|
| Transit Custom (efficient driver) | 38mpg | £2,235 |
| Transit Custom (average driver) | 34mpg | £2,498 |
| Transit Custom (heavy load, winter) | 28mpg | £3,032 |
| Difference (best vs worst) | 10mpg | £797 |
That £800 difference is two months of campsite fees, a solar panel upgrade, or a diesel heater.
How to Track Fuel Economy
The Standard Method: Tank-to-Tank
- Fill the tank to the first click of the nozzle. Note the mileage.
- Drive normally.
- Next fill-up: fill to the first click again. Note the mileage and litres added.
- Calculation:
Miles driven = New mileage - Old mileage. Gallons used = Litres / 4.546. MPG = Miles / Gallons.
Accuracy: Within 1-2% if you always fill to the first click.
The problem: Most van lifers don't track consistently. The "first click" varies between pumps. The "about 50 litres" estimate is worse than useless.
The App Method
| App | Cost | Features |
|---|---|---|
| Fuelly | Free (basic) | Track MPG, cost, per-vehicle. Simple interface |
| Road Trip | £5 (one-time) | iOS only, detailed tracking, graphs, maintenance reminders |
| Spritmonitor | Free | German, very detailed, huge database for comparisons |
| aCar | Free (with ads) | Android, tracks fuel + maintenance |
Fuelly is the best for most people. Create a free account, enter your mileage and litres at each fill-up, and it calculates and graphs your MPG. You can compare against other UK van owners with the same vehicle.
The DIY Spreadsheet
A simple Google Sheets or Notion spreadsheet works:
| Date | Mileage | Litres | Cost | MPG | Notes |
|---|---|---|---|---|---|
| 1/3/26 | 45,200 | 62.4 | £96.72 | 34.2 | Filled at Tesco, heavy load |
| 8/3/26 | 45,650 | 55.8 | £86.49 | 36.1 | Mixed driving, lighter load |
| 15/3/26 | 46,100 | 60.1 | £93.16 | 32.8 | Motorway at 70mph, roof rack on |
After 5-6 entries, you have a useful average. After 20 entries, you can see patterns.
What Affects Fuel Economy in a Campervan
Weight (The #1 Factor)
| Extra Weight | MPG Loss |
|---|---|
| 100kg | 1-2% |
| 200kg (full water + gear) | 3-5% |
| 400kg (full build + water + bikes) | 6-10% |
A full campervan conversion adds 400-600kg. That alone costs you 6-10% of your fuel economy vs an empty panel van.
What you can do: Don't carry full water tanks if you don't need them. Every 60L of water is 60kg. Empty your grey water tank before driving. Strip unnecessary gear.
Roof Load
| Roof Item | MPG Loss at 60mph |
|---|---|
| Empty roof bars | 0-2% |
| Roof bars + solar panel | 3-5% |
| Roof bars + solar + bike rack | 5-10% |
| Roof box (large) | 10-20% |
The roof box is the worst offender. A full-size roof box on a Transit Custom costs 15-20% of your fuel economy at motorway speeds. The drag is brutal. If you need the storage, put it inside or in the garage.
Speed
| Speed | MPG vs 60mph baseline |
|---|---|
| 50mph | +15-20% |
| 60mph | Baseline (0%) |
| 65mph | -5-8% |
| 70mph | -12-15% |
| 75mph | -18-22% |
The difference between 60mph and 70mph is 12-15% more fuel burned. Over 10,000 miles, that's about £300.
Van aerodynamics: A campervan is a brick. The drag coefficient of a Transit Custom is about 0.35 — worse than a car (0.28), better than a Luton van (0.45). Above 55mph, most of your engine's power is overcoming air resistance, not turning the wheels.
Tyre Pressure
| Tyre Pressure | MPG Effect |
|---|---|
| 5% under-inflated | -2-3% |
| Correct pressure | 0% |
| 10% over-inflated (front only) | +0-1% |
Check your tyre pressure weekly. A tyre that's 10psi low wastes fuel and wears unevenly. The correct pressure for a loaded campervan is stamped on the driver's door sill or in the fuel cap — it's usually 45-55psi front, 55-65psi rear (unladen vs laden).
Driving Style
| Driving Style | MPG Improvement vs "Normal" |
|---|---|
| Smooth (gentle acceleration, early braking) | +5-10% |
| Anticipatory (reading traffic ahead, coasting) | +10-15% |
| Aggressive (hard acceleration, late braking) | -10-15% |
| Engine braking (using gears, not brakes, downhill) | +2-5% |
Single biggest tip: Look 200m ahead. If you see a red light or stopped traffic, lift off the accelerator immediately. Don't accelerate towards a stop.
What Good MPG Looks Like
Real-world average MPG (loaded campervan, mixed driving):
| Van | Good MPG | Average MPG | Poor MPG |
|---|---|---|---|
| Ford Transit Custom (2.0 EcoBlue 130/170) | 38-40 | 34-36 | 28-32 |
| Mercedes Sprinter 907 (OM654 140/165) | 34-36 | 30-33 | 25-28 |
| VW Crafter (same as Sprinter) | 34-36 | 30-33 | 25-28 |
| Fiat Ducato / Boxer / Relay (2.2 BlueHDi) | 32-35 | 28-31 | 24-27 |
| VW Transporter T6.1 (2.0 TDI 150) | 38-42 | 35-37 | 30-33 |
These numbers assume a standard conversion (400-600kg build weight) and mixed UK driving (A-roads, motorways, some town).
When MPG Drops Unexpectedly
A sudden drop in fuel economy (more than 3mpg) usually indicates a problem:
| Symptom | Likely Cause | Cost to Fix |
|---|---|---|
| 3-5mpg drop, rough idle | Dirty EGR valve | £200-400 to clean/replace |
| 4-8mpg drop, black smoke | DPF partial blockage | £150-250 forced regen |
| 2-4mpg drop, no other symptoms | Under-inflated tyres | £0 (pump them up) |
| 5-10mpg drop, engine light on | MAF sensor failure | £80-150 to replace |
| 2-3mpg drop in winter | Winter diesel blend | £0 (normal seasonal change) |
| 3-5mpg drop, heavy van feel | Brake caliper sticking | £150-300 to replace |
Track monthly. A 3mpg drop that persists for two fill-ups means something is wrong. A 1-2mpg drop in December is normal (winter diesel, more idling for heating, denser cold air).
The 5-Second Daily Check
Before you drive off each day:
- Check your tyre pressures (visual check, use a gauge weekly)
- Remove any unnecessary roof load (bikes, boxes)
- Check your water tank level — do you need 60L for a 30-mile trip?
Over a year, the 5-second check saves you £200-400 in fuel.
