Probably been mentioned, but...

I was watching Eurosport just now and caught the final races of the Race of Champions. Track and rally champions competed against each other on one of those paralell loop-tracks in a stadium (Stade de France in this case). It looked like heaps of fun to do.

So I'd like to see a stadium environment in LFS, we could have multiple layouts, including a small oval for the necessary stock-car/banger racing as some people proposed.