Interesting idea, but ultimately someone is going to be stuck with the significant burden of being the head administrator. Do to the inherent risk of working on vehicles, (especially after a few ), it would probably be best to have this venture under an LLC. So now someone has to form the LLC, file the taxes, deal with insurance, collect dues, chase down delinquents, manage the scheduling, clean up after an irresponsible person covers the place in Birfield grease, etc. Said person may need to be compensated for their efforts as part of the annual dues. If you figure that a member might use the facilities 7 days (?) a year, then you could split the cost across 52 members.
I think I would be inclined to beef up the loan-a-tool program and let people fend for themselves for the garage space. As for socializing...that's not allowed anymore.