Ehi
Hertz
keddy by Europcar
Tongye
Avis
Europcar
Hiring a car at Xi'an Xianyang Airport for a week can be a great option for travel. Ehi, the most popular car hire company for this area, offers hire cars for around £127/week on average.
Yes, hiring a vehicle at Xi'an Xianyang Airport for a month is certainly possible.