Would car football with the lfs engine be fun? A few people I know have tried it with a uf1 on a server (With an alt) But maybe adding a football to urge this idea could be fun :3
Car football has been tried in various versions. In my opinion even the lighest cars are too heavy to use as ball. It is okay for the novelity but not that great because the player-cars get damaged too much.
However with Insim script some other custom game-modes have been made. Some work better and are actually quite fun. Like 'Sumo' or 'Capture the Flag' etc.
Team GLOW is one creator and host of such stuff. Like currently here: http://forum.city-driving.co.uk/showthread.php?tid=21822&pid=207549#pid207549 'Bumper Cars'