If you are staying on property make sure when you check in that you tell them you have a car.
They will print you out a pass that you put on your dashboard. This pass gives you free parking in all 4 of the parks.
If you are not staying on property but have an AP parking is free.
Parking cost $8 for cars. That really adds up if you go to the parks every day, it is worth it to stay on property, but I do prefer to have a car rather than take the busses. Peggie