Rental price is based on time and additional kilometers. The time is be based on hours, days or weeks and the time can include a set amount of kilometers. If you drive more than the included amount then you will be charged for additional kilometres. You also need to pay for the fuel you use. 

Example

The daily price of a car is 25 euros including 120 km. The extra kilometers are €0.30/km. You rent the car for 2 days and plan to drive 300 km.

The daily rent is 2 x €25 = €50
Price includes 2 x 120 km = 240 km
You’ll be charged for 60 km x €0.30 = €20

The total price of the reservation is €70