Heh, you're meant to do the render without entities (except perhaps doors), you don't want waypoints and lights etc showing up. It'd give the game away sometimes.
There's a limit to how much it can render, based on how much your pc can handle, I've just been working on a 5x5 map, it rendered fine until I added a couple of small ditches. The extra floor levels made the map crash when I tried to render it. I had to reduce the map to 5x4 before it would render, so no doubt the extra resources needed to render the sprites as well are too much for your machine.
Sometimes though if you are having difficulties rendering a map you can cut away at the tiles outside of the camera boundary, they might be cast in shadow but it's something less to render.
Screenshots look interesting, now hurry up and release something
![smile :)](./images/smilies/smile.gif)
oh you might want to adjust the vehicle's team, skin or hair colour rather than the base colour. Then you won't get red tyres.