We'll look into it. It's slightly trickier than it could be because that database field is completely free-form, so looking up an image from it or translating it is harder than it needs to be. Thanks for the input though, I've passed it along :)
In the US market every Zipcar has its name on the back to make identifying them easier, and if you're using the iPhone app you can see the license plate as well as details about the make and model.
Currently you can't tell the colour from the mobile app but it's a good idea. I've passed it along to the mobile team to see if it's feasible.