Access to the Alhambra by car is via the Ronda Sur (A-395) in the city, as private transport is not allowed to access the Alhambra from the city centre. You must go to the Granada ring road (N-323 / A-44) and take the Ronda Sur (A-395) following the signs for the Alhambra.
At the Serrallo tunnel, use the left lane and take exit 5A. At the roundabout turn left to go up Avda. de Santa María de la Alhambra and then Camino Viejo del Cementerio until you see the parking sign for La Alhambra.
In both cases you will need to leave your car at the Parking of the Alhambra which is located between the main ticket office and the Cemetery of San José. The cost for one hour is around 2,50€.