It's generally 70 to 90 minutes between stepping off the plane and arriving at your resort.
You would need a miracle (or at least a teleporter) to make it to the car care center by 6:00.
Not going to be enough time.to get from MCO to WDW on Magical Express if your flight arrives around 4:30p? I'm planning to rent a car from the Car Care Center that day and they close at 6:00p.