Most hourly bookings include 20 kilometers (12.4 miles) of complimentary distance for every hour booked - inedpendet of the car class. For example, a four-hour booking would have 80 kilometers (49.6 miles) included. Some cities come with more kilometers/miles per hour due to their size. The exact amount of complimentary distance is shown in the booking overview of the booking flow.
Should you exceed the complimentary distance, there is an additional charge per extra kilometer. The amount depends on the city and car class.