Here is some info on how to add tracks ... and where to find them.
Together with some friends I have compiled what we call a basic mp set ... let's say some tracks which are used a lot (and loved) and where to find them.

To add a track:
Download
unzip
add to the racer folder in data/tracks

Tip: racer does not seem to check if you have the correct track when you join a mp game. If you have weird results when joining a game - double check you have the correct track.

I have finally found some hosting space to put up cars and tracks - courtesy of g7|gren

For now a quick link :
http://racer.bac.ro

Schuchter V3 in two versions ... day and night. A must have as Snowball_918 made a lot of grid positions for multiplayer. Find them here

Ruudskogen
update for Ruudskogen

swiss stroll

More to come
feel free to mail me with suggestions/additions to this page