RV hosts have the ability to choose how many kilometers or miles they want to include in the rental. When viewing a host's listing and entering your trip dates, you will see how many kilometers/miles are included and what the cost is for extra kilometers/mileage in the price breakdown.

The limit of kilometers/miles per day will be noted, and you can see the cost per extra kilometers/miles by hovering over the question mark icon.
Some hosts choose to offer unlimited mileage, which will also be visible in the price breakdown:

During the departure and return inspections, both yourself and the host will make note of the odometer reading to calculate if any overage charges are due after your trip.
If so, they will be entered by the host during the closeout process. You will have the ability to review this charge and either accept or dispute it. Note that these charges are subject to RVezy's service fee and its tax.
Please note that the kilometer/mile allowance is calculated per day and not per night. If you are renting an RV for 3 nights and 4 days, and the mileage limit is 100 miles per day, you will be allotted a total of 400 miles for your trip. Any miles traveled over this amount will be subject to the charge as per your booking invoice.