Yes, you can take the ART, but it may be a little frustrating. The drivers can’t force someone to move out of the accessible seats. So, if people are sitting there—or if there is already an ECV on the bus—you just have to wait. Then there is the challenge of actually maneuvering it onto the bus. On our last trip, we ended up just walking i to the parks as it was less headache. It’s a hike, but doable. The biggest challenge was keeping the think charged. There are outlets all around the park. Technically, some of the spots are reserved for the DL ECV—from what I have been told. However, we could usually find an outlet by the exit for Space Mountain. There are some boards that list all the outlet locations.
Whatever you do, don’t get one from DL. We tried that one trip and they were all gone for the day. Eventually they found a manual wheelchair for my FIL. There are several local places that we have rented from. We have never had any problems.
Enjoy your trip!