Anyone familiar with the Racer sim? It's free, has a whole bunch of cars (including a 914 2.0) and tracks (LeMans, Nurburgring, LimeRock AX, etc). I understand you can configure your own car, and perhaps your own track.
Must have been invented by someone who lives where it snows a few months of the year!
Check it out here:
http://www.racer.nl/
http://www.racer-xtreme.com