We could do a circuit based version of this challenge that focusses on what percentage of time you could get under (or closest to) the average for a given track.
Natsoft has a shitload of info on sprints for each track in Australia, it would be reasonably simple to compile an average for each track in australia, based on this info, which could then be used as the basis for comparison. Given the thousands of entries for each track it would have to go close to being a good relative basis for comparison.
It would take a bit of time to compile the averages, but not too hard, or really easy if natsoft would run the queries for us.
3 months to build, 6 months to improve. Up the budget slightly to 2k maybe.
Also, I think there needs to be a restriction on tyres to something epically shitty like simex branded tyres, to stop people getting old semi-comps and the like.