The three common policies
Full to full
You collect it full and return it full. The fairest and usually the cheapest, since you buy fuel at pump prices. Keep the final receipt.
Same to same
Return it at whatever level you received. Common where the tank is not full at handover — check the level written on the form matches the gauge.
Pre-purchase
You buy a tank up front and return it empty. Convenient, but you pay for a full tank whether or not you use it, usually above pump price.
What a shortfall costs
Returning below the agreed level is not charged at pump price. Suppliers apply their own rate plus a refuelling service fee, which together typically run well above the cost of filling up yourself.
A few litres short can therefore cost several times what the fuel was worth.
Refuel close to the return point
Fill up within a few kilometres of the drop-off so the gauge still reads full on arrival. A station twenty kilometres away can leave the needle visibly off the mark.
Keep the receipt showing the time and location — it is the evidence if the supplier disputes the level.
Use the right fuel
Misfuelling is expensive and is never covered by insurance. Confirm petrol or diesel at handover and check the label inside the fuel flap before the first fill.
For hybrids and electric cars, confirm the return requirement separately — a charge level, not a tank level, may apply.