Hello, Amie!
Welcome to the Disney Parks Moms Panel! You are welcome to park in designated accessible parking areas, providing your father has a valid, accessible parking placard. Otherwise, you will be directed to Standard
Parking, or you can pay an additional fee for Preferred Parking, located closer to the entrances. From the Magic Kingdom parking lot, you can take a ferry or monorail to the theme park admission gates. Both are accessible, so your dad will have no problems driving his ECV on the provided ramps.
As you plan your trip, be sure to take a look at the
Guests with Mobility Disabilities page. Some attractions will require your father to transfer from his device to the ride vehicle, and others where he can experience that attraction while remaining in his ECV. Most attractions will allow him to use the unit throughout the queue; however, there are a few that require the use of a provided wheelchair to access the queue.
I hope this helps your planning! Please visit us again should you have additional questions.
Missy