cowboy you're gonna hate me for this video
anyways, the idea came up from the fact that this advertising thing is really long and wide and errrr i could see some people not making dedicated images just for the advertising on this vehicle, so some kind of scaling option provided within the images would be a nice change of pace rather than having a bunch of stretched prius advertisements
of course, maybe i shouldn't try and fit a dead meme on the advertising things, but it's an exaggerated example so the point goes across

Not possible. The image application and parsing is handled internally by MC. It's essentially a UV-mapped texture to a shape. No changing that dynamically. Certainly not when the mapping for the same image would be different for different things.