Hello, Rebecca!
Congratulations on your upcoming Walt Disney World Resort vacation! Since my mother has limited mobility issues, she uses an Electric Conveyance Vehicles (ECV) to tour the parks and resorts. She loves that she doesn't have to worry about missing any of the magic!
You will find that
ECV Rentals are available in all four theme parks and Downtown Disney. Keep in mind that there are limited quantities, available on a first-come, first-served basis and reservations are not accepted. It's also important to note that ECVs must remain in the park in which it was rented. So, this may not be the best option if you plan to park hop or explore resort hotels.
In my experience, my mom has more flexibility in how she tours Walt Disney World Resort by renting an EVC from a Disney featured provider. She can take the ECV everywhere! We have had great experiences using Buena Vista Scooter Rentals. They offer a variety of ECV models and even deliver (and pick up) the unit to our resort. My mom can pick up the ECV at Bell Services when we arrive, and be ready to tour without delay! You can find a list of Disney featured providers at the bottom of ECV Rental page.
I am sure that you and your parents will have a wonderful May vacation! Let me know if I can answer any future questions that you may have.
Have a magical day!
Missy