Why the Fuel Policy Matters
The fuel policy on your car rental can add anywhere from nothing to €50+ to your final bill. It's one of those details that seems minor when you're comparing base rates online, but can make a significant difference to your total cost. Understanding the three main fuel policies — and choosing the right one — is an easy way to save money.
Full-to-Full: The Best Deal for Most Travelers
Full-to-Full (also called Full/Full or Same-to-Same) means you receive the car with a full tank and must return it with a full tank. If you return it with less fuel, the rental company will charge you for the missing fuel at a heavily inflated rate — typically €2.50–4.00 per liter versus €1.50–1.80 at a gas station.
This is almost always the cheapest option because you're buying your own fuel at normal pump prices. The only downside is the inconvenience of finding a gas station near the drop-off location before returning the car. But this is a minor inconvenience that saves significant money.
Tip: Use Google Maps or Waze to search for gas stations near the airport or drop-off location before your return time. Fill up at the last convenient station — it doesn't need to be the very closest one, as long as the drive from the gas station to the drop-off doesn't use a significant amount of fuel.
Full-to-Empty (Prepaid Fuel): Convenient but Expensive
With this policy, you receive a full tank and pay for the entire tank upfront at the counter. You can then return the car with any amount of fuel — even completely empty — with no penalty. It sounds convenient, and it is, but there are two significant catches.
First, the per-liter price the rental company charges is almost always higher than pump prices — sometimes 20–40% higher. Second, you're paying for a full tank regardless of how much you actually use. Unless you return the car bone dry (which requires careful planning), you're effectively giving the rental company free fuel.
On a typical one-week rental where you use half a tank, the combination of inflated pricing and unused fuel can cost €30–60 more than Full-to-Full. That said, if you're returning the car very early in the morning or in a rush, the convenience might be worth the premium.
Same-to-Same (Partial): Rare but Fair
Some providers hand you the car with a partially full tank (say, 3/4 or 1/2) and ask you to return it at the same level. This is reasonably fair but can be tricky to gauge precisely. If you return it with less fuel than required, you'll be charged the rental company's inflated rate for the difference. Many travelers accidentally overfill to avoid the charge, which wastes a few euros but avoids the larger penalty.
Look for Full-to-Full Fuel Policies
The best rental deals include a Full-to-Full fuel policy. Compare options across providers.
Compare Rental Deals →Fuel Type: Petrol vs Diesel vs Electric
Always check which fuel type your rental car uses before filling up. Putting petrol in a diesel car (or vice versa) is a costly mistake — repairs can cost €2,000–5,000 and are almost never covered by CDW or insurance. In Europe, diesel nozzles are typically larger than petrol nozzles to prevent misfueling, but don't rely on this safety feature alone.
Diesel is generally cheaper than petrol in most European countries and offers better fuel economy, making diesel cars a good choice for long road trips. In the US, the difference is smaller and varies by state.
For electric rental cars, make sure you understand the charging policy before driving off. Some providers require you to return the car charged above a certain percentage, while others handle charging themselves.
Current European fuel prices are tracked by the European Commission Oil Bulletin.
How to Choose the Right Policy
For the vast majority of rentals, Full-to-Full is the best option. It gives you the lowest cost per liter, the most flexibility, and no need to pay for unused fuel. The only scenarios where Prepaid Fuel might make sense are extremely short rentals where you'll use most of the tank, very early morning returns where gas stations may be closed, or airport drop-offs where the nearest gas station requires a significant detour.
Avoiding Fuel-Related Surprises
Take a photo of the fuel gauge at both pickup and return. Some travelers have been charged for "missing fuel" when they returned the car full — having photographic evidence with a timestamp prevents disputes. Also, keep your final fuel receipt as proof that you filled up near the return location. These simple precautions take seconds but can save you from unfair charges.