Billy takes approximately 100 litres to fill.
At present that will cost around £1.12 to £1.35 per litre, depending on which service station you use. Note that motorway services will always cost more.
1. The tank is on the passenger side.
2. Open the passenger door and look at the bottom right.
3. Flip open the second smaller door.
4. There is no petrol cap - just put the fuel nozzle in and fill him up!