Centauro is a Spanish rental car company that operates the Full/Empty fuel policy, when you make a reservation for more than 3 days.
Some useful information regarding their location at Valencia airport (Manises):
Like most of the car hire companies at Manises airport,Valencia Centauro have no desk at the airport terminal . Some rental car suppliers like Avis, Hertz and Europcar do have a desk , but ALL provide their customers with a prompt bus service to the nearby facilities in Manises Polygon, where the rental car fleets are located. This bus collects and delivers the customers outside Departures. On your confirmation voucher it explains this, so whether you arrive by air or to the airport by taxi, for example, you should stand just outside the airport in front of Departures and await the Centauro shuttle bus.
If you are not arriving by air, you can go directly to their office and collect your rental car. When returning a car, then you always go to the same office.
Please note that most spanish car rental companies operate a full out empty return policy.
Click here for additional advice on Tipoa's FAQ page
With Centauro if you rent a car for 3 or less days, you have the chance of returning it with the tank full and the initial amount of money you paid as a deposit for the fuel when you collected the car, will be reimbursed.
I recommend that you take this option, as they charge you a premium amount for the initial full tank of fuel. So it is best that you do not return the car empty.
Filling up the tank before returning the rental car is not a problem as there are many petrol stations at Manises Polygon. i.e. just a few meters behind Centauro local there are a Repsol and also a Galp petrol stations.