The fuel policy is shown underneath the picture of each car. It will be either:

• Full to Full: The car will have a full tank of fuel when you pick it up, and you should return it with a full tank to avoid any additional fuel fees;
• Same to Same: You should return the car with the same amount of fuel it had when you picked it up (which should be marked on your rental agreement) to avoid paying any additional fuel fees. 

Check the Rental Conditions to see more information about the car's fuel policy.