Hey all,
Found this while cruising around the aussiemanga forums, it's a funky web-application that allows you to select car make, model, complete with customization such as car colour, rims, ride height, and when you're done, put it in a live scene and then you can have it send the finished render to you.
Envizio Wheel Wizard
It requires an external plugin to work, but it only takes 1/2 a minute to download the plugin, and then you're off and racing.
Here's an example that I created: