A little quick-trick i use for the FXO and other sedans:
starting with a 2048 sized skin, use guidelines to divide the image up into it's binary sections (halve's quarters, eighths - you'll find that each of these coords is given by adding common binary numbers e.g. 128, 256, 512, 768, 1024, 1536 (1024 + 512).. zoom up on the image to drop the guideline exactly), you'll begin to see the components of the car falling within defined boxes*.
But concentrate on the guideline at 1536, and place one at 0 too. next, make your canvas 512 pixels wider. Lock the image over to the right so that the newly added area is on the left. make sure you have lock to guidelines switched on, and box-select the sides and roof/bonnet section as defined by the 2 vertical guidelines. Then, use edit/transform/scale to pull the left of your selection to the left of the image area. this effevtively makes the roof/hood/side sections a 2048 square image itself.
At this point, you should do your paint thing, apply logos, etc.
Now, you may want to set up a macro or action to save your work as a jpeg, then you need to open that jpg - the guidelines should still be there, use them to select just the stretched-out section, and edit/transform/scale it back to it's original size. finally, crop the image back to 2048 wide. resave. you need to do this repeatedly if you're aligning stripes and logos across different panels, and updating the skin in the LFSviewer regularly.
it's not a 100% system for all of the sedans, at least i assume so - i haven't tested it, but it's an only slightly bigger step to taking each of the pieces defined *at this point, and stretching each component over screen-captures of the orthagonal views from the LFSviewer (top, side, front, back), then, once finished, cutting and pasting it back into it's original space in the grid, using the guidelines to stretch it back to it's exact original aspect ratio. I've used this technique to make an FZR template that works perfectly - but! - only when viewed in an orthagonal view. here's why:
Whenever a panel slopes away from the purely vertical/horizontal it distorts. the more it is sloping away the more it disorts. look at the insides of the front vents to see this happening. this is because of the planar coordinates used to apply the skin to the car model. the use of the word 'skin' is deceiving as it implies a wrapping procedure, but it's actually more like the grain throughout a piece of wood or the lettering inside a stick of Blackpool rock-candy, it's being projected
through the mesh.
but yeah, the binary thing is fascinating don't you think? it's a technique used by texture mappers in almost all games, as its easier to programme using set sectors defined by halves, quarters, eighths, and so on, and the tiling positions are all defined by 0.5, 0.25, 0.125 increments. i'm sure it all gets a lot more complex, but that was a eureka moment for me
when i started out as a computer animator we had a seperate texture map for every part of a model, but you couldn't do that for a game - it would get very large, very quickly, and it would be a nightmare trying to find all of the required components for alteration. actually, it was. i'm not an animator any more, btw.