You can easily get to Fez, Volubilis, and Moulay Idriss without renting a car, but the latter two might warrant a day rental, as much for the surrounding countryside as for the destinations themselves.
For international rental agencies such as Hertz and Avis, the Fez airport at Saïss, 30 minutes away on the A-2 freeway, is the nearest option. For day rentals at reduced prices, Meknes has several local agencies listed below.
Bab Mansour Car (8, rue Idriss II. 035/52-66-31). Stop Car (3, rue Essaouira. 035/52-50-61). Zeit Wagen (4, rue Antsirabe. 035/52-59-18).