Dane Johnson has a very neat tool for Nascar Racing called NRHQ. You can
download it from http://www.racesimcentral.net/~danej/
The software allows you to :check lap times, view replays, and chart them,
and my favorite "tweak setups". It takes suggestions from you the driver
such as "loose entering corners", "pushing in middle of turn", etc. and
gives you choices of what could be wrong with the selected setup. You then
go and apply the change and the software even writes a new setup with that
singular change in it.
You can then go out and try it and if it still needs something else you can
continue on this way until it feels right.
My question is, "how many people here would be interested in a version of
this for GPL?"