I'm not going to say it's easy to do a travel portable
scooter in and out of a car, but it's doable.
Most portable travel scooters go between 100 to 125 pounds. Most breakdown into 4 or 5 pieces. There are u-tube videos you can view to show you how. It's much easier if two people handle the base of the scooter together. The battery will probably be the heaviest piece at 35 pounds.
One trick if you get by at the resort without a scooter is to just take the battery into your room each night to recharge; you don't need the whole scooter. This saves on the in and out of the scooter with the car.
For some, it's not worth the savings of an outside scooter rental and they just rather rent at the parks. Then, you don't worry about getting the scooter in and out of the car. You don't charge it every night. The smaller models don't have the battery power of the larger ones. If you want long hours at the parks you may have to upgrade your scooter rental to a two battery scooter which will be bigger and heavier.
Body weight is a factor on the model of scooter you need to get, as well.
Chances are you have a local mobility store in your area. You can always visit one of these stores and you can test it out there. The popular model usually everyone rents is a Pride to Go scooter. The store will let you test drive it in their parking lot usually and most will let you dissemble and put it into you car and out again.