Bruno lifts are the best. I have a side loader in my MiniVan. It's on a track and my Scooter sits right behind the drivers seat, makin it easier to lift it in or out, without my having to get out of the Car.
I don't know if this kind would be practicle for a powerchair, but it may be worth a look see.
Here is a video of it.....
http://www.advanced-lifts.com/Video_...r_lift_II.mpeg
Good Luck..