...BUT... and this is a very big but. What's wrong with a trailer? You can take the trailer off and use the tow vehicle for something else. With this, it will always and forever be for one purpose and one purpose only. I just don't see the practicality of such a specialized vehicle. On top of that if this is for your track/rally car, you are going to need to carry more than just two people, a car and some sandwiches. When I go to even a rallycross my car is FULL. Floor jacks, jack stands, every tool you might possibly need and some you probably wont, rally tires, spare fluids, lights, etc. etc. And since you are towing the vehicle there's a good chance it's purpose-built and you are going to have even more gear so you'll need a 2nd vehicle to haul that. Like I said it's just not practical. Oh well it's a neat idea nonetheless and certainly a cool project.
great idea for the owner of a used car lot or a mechanic that does pick up and/or delivery. and it would make a great support vehicle for my Ariel Atom.