Take a look in the disABILITIES section of this forum.
Lots of discussion of the merits of renting off-site as against in the parks.
Plus a 'sticky' thread with all the contact details of off-site ECV rental companys in Orlando.
Andrew
PS ECV=Electric Convenience Vehicle = Mobility
Scooter
Off-site rentals work out cheaper than in the parks and can be delivered to your hotel, so you can use them everywhere. Disney Parks - Universal - Sea World - Shopping Malls etc. But less convenient if you are not staying at a Disney Hotel and have to transport the scooter.
Disney has ECVs to rent in the parks, but you can't take them out of the parks. More expensive and Disney can run out of them in the peak season.
If you are staying on-site at a Disney Hotel, an off-site rental for the length of your stay is your best choice because on-site Disney transport is all wheelchair/ECV compatible.
If you are staying in a hotel or villa not on Disney property, remember that you will need a larger rental car or van and you will need to dismantle/reassemble the ECV every time you go to a park. An alternative would be to use 'wheelchair' taxis, which operate in the area.
If you are travelling outside of the main holiday periods and don't know if you want the ECV
every day, renting in the parks is an option.
Andrew