we have a minivan (2013 dodge caravan...very popular type with the rental companies) and I also have a Go-Go Elite 3-wheel Traveler. Can guarantee that they come apart easily, are very easy to operate, and make the parks a lot of fun. They are comfortable, they are stable...but do keep in mind they have weight limits on them (the Go-Go is a small
scooter, so I believe the weight limit is 225. A heavier person could ride it, but the battery will drain much more quickly when you exceed the weight limit.)
Edited to add:
Hubby just measured and says yes, the GO-GO would fit behind the 3rd row of seats. You would have to take the components apart, and put some on their sides to fit, but the pieces would fit. It does break down into component parts very quickly, no tools needed and goes back together very quickly too...less than 2 minutes once you get the knack. DO watch the video on the rental page. Have used Apple scooter rentals in both Orlando and in Las Vegas...good company. If anything goes wrong with scooter, they are there in a flash. WARNING: make sure the scooter is plugged in every night, even if it appears to have a full charge. The charge indicators are kind of like car gas tanks...takes "forever" to get to "half", and then goes from half to empty way too quickly. As long as you plug them in all night, they will go and go for like 10-12 miles (more than you would use in a park.) AND always make sure to keep the charging cords in the pocket on the back of the scooter, just in case you would need to re-charge in a park...shouldn't happen, but just in case!
The other suggestion...if the person using the scooter has a handicapped parking hang-tag, tell them to bring it with you to Orlando. At the Disney parks, there is no way to ride a scooter onto the parking lot trams so if you park in the regular parking lot, the person on the scooter has to drive through a lot of parking lot while the rest of you hop a tram. If you have a handicapped hang-tag, hand it when driving into the parking lot, and when you get to the people directing parking traffic, slow down and point at the hang-tag, they will direct you to the handicapped parking If they do not have a handicapped parking tag, stop when you get to the people directing parking lots and tell them you have a mobility scooter...they will direct you to medical access parking that is right next to the handicapped spaces so you'll be close to the park entrances (or close to the transportation .& ticket center for Magic Kingdom.)