The reason I even brought this up was that I had been thinking about the possibility of doing some enduros in the future (in my car), and my ideas were more along the lines of what Matt was saying; i.e. that a group of 3-4 friends would get together and split the costs of running a particular event. Aside from a very clear understanding of who would be responsible for damage from accidents/gross stupidity I wouldn't have expected the other drivers to cover costs beyond the event they were participating in. I just wasn't sure if that was a really stupid way to look at it, or if there were some out there who did it that way.
When we ran the Smurf in the enduros, the arrangement was as follows:
Team split the cost of preparing the car for the full distance, all consumables, the rehab after the event including damage. If it was worn and needed replacement, it was a team cost. If it broke during the event, it was a team cost. If it needed replacement after the event, it was a team cost. If an ITA driver who shall remain nameless was in the car when the brand new engine overheated, it was a team cost.
If a nameless prod driver turned it turtle in turn 10, that was a team cost.
The opportunity cost of labor for prepping the car was included.
The buyout price was established in advance and I got to keep the car.
It only works if the entire team trusts each other, likes each other and would like to keep it that way afterwards.
The way I figured it, I ended up with a car that was gone over with a fine comb twice and I got handling feedback from 4 other drivers. The depreciation was something I just ate because I wanted to run an endurance event and wanted to do it in a car I knew.