How OTW works
The cheapest fuel on your route isn't always the cheapest price. A station 3¢/L cheaper that's 8 km off the highway can lose you money. OTW works out which stop is actually worth taking.
Three steps
- 1
Tell us your car
Year, make and model. We look up its fuel consumption and tank size.
- 2
Say how much fuel you have
Slide to roughly where your gauge sits. We work out how far you can go.
- 3
Enter your trip
We find every station near your route and rank them by real dollars saved.
Why the cheapest station can cost you money
Here is a real example from a Melbourne to Sydney trip, filling 40 litres:
| Station | Price | Detour | You actually save |
|---|---|---|---|
| Cheapest price | $2.345/L | 12.5 km · 15 min | $5.38 |
| Best value | $2.349/L | 2.3 km · 3 min | $7.62 |
The cheaper station is 0.4¢/L less — and leaves you $2.24 worse off, after 25 minutes of extra driving. That gap is the whole reason OTW exists.
How we work out your range
We deliberately under-promise. Official fuel figures are measured in a laboratory and run roughly 20% optimistic against real driving, so we cut them back before doing anything else.
fuel on board = tank size × how full it is usable fuel = fuel on board − reserve real usage = lab figure × 1.20 range = usable fuel ÷ real usage × 100
The reserve is 5 litres, or 10% of your tank, whichever is larger. We hold it back so you're never sent to a station at the exact edge of empty. Overestimating range strands people; underestimating it just means you fill up slightly early.
How we rank the stops
Every station near your route is scored on what you'd save against the average price along that route, minus the fuel burned reaching it.
litres to fill = tank size − fuel on board saving on fuel = (route average − station price) × litres to fill detour cost = detour distance × real usage × station price what you save = saving on fuel − detour cost
You can sort three ways: Best value (what you actually save), Cheapest (lowest price, whatever the detour), and Least detour (barely off your route). Every stop shows its full working — tap “show the working” and check our arithmetic.
Where the data comes from
- Fuel prices come from the state government fuel price feeds, covering roughly 9,000 stations nationally. Each price shows when it was last updated, and anything older than 48 hours is greyed out.
- Which cars matter comes from BITRE's Road vehicles Australia — a census of what is actually registered and on the road here, rather than what sold well.
- Fuel consumption and tank sizes are currently our own estimates, drawn from manufacturer specifications. We are in the process of licensing the Australian Government's Green Vehicle Guide data to replace them with official ADR-tested figures.
What we don't know
We would rather tell you this than have you find out on the road:
- Fuel consumption and tank size are estimates until the official data lands. If we have your tank size wrong, type the real one in — it's in your owner's manual — and we'll use that instead.
- Detour distance is measured straight-line to the station and back, not turn-by-turn. It will understate detours where the station is across a divided highway.
- Prices change through the day. We show you when each one was last updated so you can judge for yourself.
- Your real range depends on load, terrain, traffic, tyres and how you drive. Treat our number as a floor, not a promise.