What I am considering is a lift gate system capable of getting a car to the box bed. There are a number of kinds of standard (rail, cantilever, tuckaway etc... liftgates with the most common in the 1500-6500 lb range such as Maxxon types.
My truck has cargo swing doors as opposed to a roll up which makes rail type difficult unless I replace the box which seems like no big deal plenty of boxes out there 20-26 ft long. I picked my truck based on the milage mostly and the sleeper cab and air suspension and my box preference got nixed when this one came availble.
The kind of lift I would like to find is a rail type in the 4000-8000 lb capacity with the long platform used on the high end car transporters or "NASCAR style" that lifts to upper deck on those type trailers. I dont see any of the web manufacturers making them with the extended platforms long enough for car. I do see the up to 96 in. which is getting pretty close though.
Ultron even has a 96 in 6500 lb cantilever.
Racingjunk.com has an example
here is an expmple with lift in mid position