Ariz. Rev. Stat. § 48-4234
B. The board shall set the car rental surcharge as follows:
D. The surcharge does not apply to the lease or rental of a motor vehicle:
2. Used in an employee vanpool arrangement for a group of at least seven but not more than fourteen passengers including a driver who meets all of the following conditions:
(d) The driver receives no compensation other than free transportation between the driver's residence and place of employment, plus limited personal use of the motor vehicle consisting of not more than twenty per cent of the mileage use of the motor vehicle for either: