If the source image is exactly this, but it's stored as NPOT, then it's almost certainly *supposed* to be offset from the center due to it's use in the game (try some other images, try some cars etc). If not then there simply must be additional information in the game data somewhere that gives you the true image size.

The point is that you shouldn't have to remove any pixels, if it's NPOT then why didn't they save it clipped to the visible pixels in the first place? why did they waste space? and if so, where's the additional information telling them what the usable portion of the image is?

Removing black pixels is not a good idea, you can't be sure that the original artist didn't actually have some blank pixels down one side, this can't possibly be the solution because why would they have this additional costly step in a commercial game when they could of just stored the image without unused pixels?

Again, if this is the source image then it's supposed to look like (A) (with transparency) in the game, your solution is correct, it's correctly mapping the source image you posted to the quad only by modifying the texture coods. it's the source image that has the blank space, not as a result of your calculations.