A database would be a brilliant idea I think, a registry that would hold static data (VIN #, Engine #, colour, year, model number and spec) as well as 'dipstick' data at certain points in time (kilometres and rego plate e.g. "in 2009/04 it was sold with 242,000km with lic. plate "2SIK"). Would just need to be a plain Excel file, could be kept on Exec server and updated by one or a handful of SAU people.
Guys and girls interested in a specific car can ask the execs to query the database based on a parameter such as a licence plate, or VIN #; if the search returns no matches, bad luck, but otherwise it could save someone a lot of woe.
The database itself would remain confidential (and no addresses or owner details for the cars would necessarily be kept). Just those details for vehicles matching specific queries would be shared with the person making the enquiry.
The database could hold not only members' cars (cars we know have been owned by people on here) but also cars being sold by dealers. If one of us goes to inspect a car at a dealer without the real intention of purchasing (such as a "Nur"), gets the VIN #; it can be logged on the database for future record keeping.
Again, awesome idea.