I actually made an InSim very similar to this (lost source though).. It tracked the max distance, fuel used and average Miles Per Gallon. Though this never saved any stats, it just worked for that session
I may have some free hours a week after college, And now have nothing to do since my LaunchControl was updated to 6E...
If I see enough demand for this, in this thread I will look into writing an InSim that does save the distances for each car on each track, as well as the overall distance for each car. With an InSim GUI showing current distance, in Km or Miles.
Though this will only be done in my spare time from life, college and the girlfriend (hates me sitting programming when she's around xD)
So if anyone else is gonna have a go, let me know