Which Fuel Policy Is Cheaper?
The cheaper car hire quote is not always the cheaper booking. A supplier can advertise a low rental price, then add a prepaid tank, set its own price per litre and charge a service fee at collection.
To compare two offers properly, include the fuel policy in the total. Do that before entering payment details, not at the airport desk.
Why the headline price can mislead
With full-to-full, you receive a full tank and return it full. You pay the advertised hire price, then buy only the replacement fuel your trip uses at a normal station price.
With prepaid or full-to-empty, you pay the supplier for a complete tank. The supplier may use a higher price per litre, add a service charge and keep the value of whatever fuel remains when you return the car.
That unused fuel matters. A short airport-to-resort holiday may consume less than half a tank, but a no-refund policy charges for all of it.
Find these three figures
Do not compare policies until the offer or supplier terms show:
- The supplier's price per litre. This may differ from nearby station prices.
- The fuel service fee. It may appear as a handling, refuelling or administration charge payable at collection.
- The unused-fuel rule. Check whether unused fuel is refunded and whether a fee is retained even when a refund applies.
“Fair fuel policy” is not enough detail. Open the terms and look for the actual policy name, anything payable locally and the refund wording. If those figures are unavailable before payment, the advertised total is not yet a useful comparison.
Compare the real trip cost
Here is an illustrative comparison, not a quote from a particular supplier.
Assume a seven-day trip uses 18 litres, station fuel costs 1.60 EUR per litre, the prepaid supplier charges 1.90 EUR per litre, and the car has a 45-litre tank.
| Offer A: full-to-full | Offer B: prepaid tank | |
|---|---|---|
| Advertised hire price | 220.00 EUR | 175.00 EUR |
| Fuel-policy cost | 28.80 EUR for 18 litres used | 85.50 EUR for a full tank |
| Service fee | 0 EUR | 25.00 EUR |
| Unused-fuel refund | Not applicable | 0 EUR |
| Real trip cost | 248.80 EUR | 285.50 EUR |
Offer B looks 45 EUR cheaper in the search results. After its fuel policy is included, it costs 36.70 EUR more. The renter also returns roughly 27 litres already paid for.
Use your own trip rather than copying these assumptions. A transfer-based beach holiday may use very little fuel; a long road trip may use the whole tank.
Can prepaid fuel ever be cheaper?
Yes, but the conditions are narrow. The prepaid offer can win if its rental-price saving is larger than:
- the supplier's fuel mark-up
- the service fee
- the value of fuel you will return unused
It becomes more competitive when you expect to use nearly the entire tank and the supplier's extra charges are low. Convenience may also matter if an early flight makes refuelling difficult, but treat that as a service you are buying—not proof that the offer is cheaper.
The calculation is simple:
- Full-to-full total = hire price + fuel actually used
- Prepaid total = hire price + full-tank charge + service fee − any unused-fuel refund
What RentaCarBestPrice includes
Full-to-full is standard:
RentaCarBestPrice does not add a prepaid tank calculation to a cheaper-looking hire price. You receive the car full, replace only the fuel you use and return it full. Full cover and no credit-card deposit hold are also included, so the booking comparison is based on the costs that actually apply.
When comparing offers, add the unavoidable charges first. A low headline rate is useful only if it remains low after the supplier's fuel terms are included.
See current options for Alicante Airport car hire or Valencia Airport car hire. For other airport pricing practices, read Car Hire Traps at Spanish Airports.
Sources: European Consumer Centre Spain and the European Commission's car-rental transparency commitments. Last checked: August 2026.