No rental fee is due and owing for any complimentary rentals. Such an agreement does not require the customer to pay a charge directly related to the use of the vehicle. A complimentary rental is done strictly as a courtesy to the customer. Discounted rentals, however, are not complimentary.
Example 1: A rental company rents out a motor vehicle under a rental agreement providing for several additional "free" days of rental. The free days are considered a discount, and a rental fee is due for those days as well as for the days that are charged by the rental company.
N.J. Admin. Code § 18:40-1.5