Its called annealing..... annealing plastic temporarily changes the surface energy. When you flame the surface you want to take a torch or heat gun to the surface of the plastic (of course not long enough to melt it or make it rubbery and soft). It will change the properties of the surface of the plastic for 20 minutes or so and when done the vinyl should adhere properly. Best option would be to use a high tack vinyl but I have really only seen high tack in print vinyl.
How about wrapping the entire inside ceiling of some buses (we have done a few dozen of these)