I don't know anything about the preferred parking, but I still have an opinion!
If you just spent X amount of hours in the Disney Park or Parks, does a 15 minute delay to get to your car really matter? If you have a disabled person with you, it could certainly matter, but otherwise my advice is just use whatever extra time it takes getting to your car to talk about what a great day you just had. There's a good chance that this will be your only opportunity to do this because you will all probably be asleep 20 minutes after you get back to your room!!