Which of the following can be considered an additional service to a rental agreement?

GPS navigation is considered an additional service to a rental agreement because it enhances the customer’s experience by providing a convenient way to navigate unfamiliar areas. Rental car companies often offer this as an optional add-on because it involves extra equipment and may come with an additional fee. The inclusion of GPS can assist in route planning and improve overall travel efficiency, making it an attractive option for customers who may not be familiar with the area they are visiting.

In contrast, free fuel on return does not qualify as an additional service; rather, it is often associated with the standard return policy for fuel. Complimentary insurance may also be tied to the basic terms of the rental agreement depending on the renter's personal insurance or credit card benefits. Longer rental periods without additional cost typically reflect a standard agreement term and wouldn't be considered an additional or optional service; instead, it simply implies the rental company is being flexible with terms that are commonly associated with customer loyalty or special promotional arrangements.