What type of tank regulations are there?

In most cases the fuel policies you find on carhiremarket.com are full-to-full, meaning you receive the car with full tank of fuel and you will need to return it with a full tank of fuel. Some car rental companies (especially in the United States and Southern Europe) have a full-to-empty fuel policy. For this requirement you receive the car with a full tank but you need to return it empty as you will not be refunded for the extra petrol left in the tank. The fuel policy can be found either on the website or in the terms and conditions of the supplier.