Here's my 2 cents for what it's worth - that said I can't see me being part of this as I have enough trouble getting my own stuff done around the house let alone taking time out to 'have a go'.
* I think you would need to have a list of who is part of this and that may mean some cash contribution to 'buy in' and a designated holder of the funds. This cash would cover some routine wear & tear and the chance to buy some parts off others on this forum that will make it go faster. Then you have to agree to how many events you get to go in so it is shared around. If its your event and you don't need it or can't make it then you can allocate it to someone else or swap events etc.
* The red mist will decend whoever is behind the wheel (bragging rights for fastest lap as the only variable is the 'spacer' as Paul Morris once described the driver). That will stretch the car beyond capacity at some point - read BOOM! BANG! CRUNCH!
* How do you cover insurance when its in an event (Ok designated driver would pay and organise but is there a problem in the event of an incident - worse still if someone (spectator) is hurt - who is the owner to sue?
* Why not make it a 'rent a drive' - charge a fee for the privledge and if you bend it you buy it. Fee is per lap or per event type thing (Brownie - didn't someone do this with Gemini's?). That way the income can cover the bits that may need to be replaced on a regular basis or regular costs - say club (?) rego & 3rd party etc.
I'm now opening my 4th stubby...................