I guess the idea here is to give your car a "vintage" look. A high-end auto shop in the U.K. has started customizing new cars . . . to make sections of them look RUSTY.
They did it with a few panels on a brand new Land Rover, where two sections of the hood are covered in rust, plus two vents on the side. So instead of the whole thing, it's more like using rust as an accent color.
For the right price though, you can have your entire car rusted up if you really want to. And they can seal it to keep that FRESH rust look. Or you can leave it alone and let the, quote, "natural course of corrosion" continue.
(Here's a photo.)