If you will have 6, plus luggage, plus an EVC, you will need an extended vehicle. If you are just transporting people and the EVC, I have done this in a Sienna mini and a Traverse crossover just fine.
I remove the seat, basket and batteries of my sister's Buzzaround XL and then put it in the rear parallel to the third row, then I put it in park so it does not roll. In my Traverse, I put the batteries behind the back wheels and the then the seat is placed on the scooter deck with the handle laying on it. In the Sienna, I do similar, but I sometimes just put the batteries, back into place if I do not have room to the side of the wheels.