they need to fit onto, you get two different results. This is where you have to use your "artistic license" and fudge some things. Now they have white-light scanning, which would be a good way to digitize body parts. Very expensive machine, especially if you need one big enough to fit a 1:1 car into. So that's how you could get the general shape of a body. Then you can just shrink it to whatever scale you want. But to make that body fit a certain existing chassis, or interior? That would be a very tall order, way beyond anything I could do. You also must realize that even the best 3D printer can only print features down to 0.XXX" size, so things like body gap lines probably need to be made bigger than "real life", and things like scripts will probably not be printable at all (to scale). You almost need to tailor your design to the printer you plan to use, because different printers and different materials all have different resolution capabilities. There is a lot more to it than just pushing buttons!