I need to reiterate and reinforce minnie61650's comparison between off-site
ECV rentals and the ones Disney rents.
Disney's are larger and MUCH harder to maneuver. I never noticed it before my last trip. I'd alway rented inside the parks. I never even noticed much difference among Disney's, Universal's and Sea World's equipment. But I broke my hip last year; that, combined with worsening arthritis and solo travel, convinced me to look off-site (btw, Randy's Mobility is another good supplier).
Well, the
ECV I had in September 'chose' to simply stop working inside Buzz Lightyear. Two Tomorrowland managers were called, and they ended up making arrangements for somebody from wheelchair rental to bring me a 'loaner' ECV to get to the front of the park and take up there (where the rental company would pick it up the next day and bring a replacement to my Resort).
Well, aside from the bulk and the lack of speed - a good thing, I guess, given that nobody would move

out of my way, the Disney
ECVs require you to flip a switch and press the same throttle to go forward and backward. It's a REALLY good thing I only had to drive Disney's equipment that short distance!