Nice idea. I was just installing some of that window film in my fridge - it's very transparent plastic, but not very durable. It's very thin, and susceptible to punctures and tearing once shrunk.
Here's a picture of body-colored wheel covers. I don't think you could pull it off on a red car.
If the window film doesn't hold up, you could use it as a mold for a fiberglass wheel cover, which could then be painted a dull aluminium color like the stock wheel covers.