Really just needs to be a big Excel Spreadsheet, don't you think? ...with a "notes" field.
Chassis|MY|Ext. Color|Int. Color(s)|Options|Location|Date/miles stamp|Notes
Start it that way - and then whoever mods the sheet can add fields and let owners know there's more information they can add. Easy-Peasy.
Here's an example
000179|2012|Vol.Orange|BlackAlcantara|All Carbon, including CCBS and SLW Wheels in stealth finish, sports Exhaust, Iris.
Notes: "Having finally found the perfect pair of red trousers amongst my collection, I took 000179 to her first car show (Leicester Ladies Bruncheonette and Concours d'Elegance). Selecting the precise pair of red trousers was more difficult than I had thought it would be - what with worries about the clashing with the brilliant orange paint and all. My worry was four naught, however as they clashed less with the paint than I imagined. It was raining that day, and, me mum having died the previous Sunday (or maybe Saturday - I can never remember), I wasn't in the sunniest of moods so the weather was cooperating. I noted the tea was slightly too too milky as I found my friends, Nigel and Simon standing near their respective cars. For whatever reason, Nigel had brought the Virage (which was still on the flatbed, and would likely remain there (as the tyre rubber has become affixed to the flatbed's carriage rather firmly over the past year). ...Nigel has finally purchased the flatbed which is a godsend as it has turned out to be the cheapest, most effective tool in the Virage's toolkit. Simon was in his Caterham 7, fresh gnat-splatters still adorning his ruddy cheeks, a testament to the fun he had on the ride from Dorcester. We made sure Virage Jokes 1-9 (including 6a which Simon positively RIPS!) were told to all passers-by (as well as answering all the questions regarding the Caterham's inability to tow a carvan of any significant sort). Molly Padwell then showed up (oooh me I would love to give her a good shag). Pipe started to gurgle whilst talking to her - ooh what a giveaway. Signficant race history with period F1 and LeMans drivers, including multiple wins and world championships; many years in a prominent collection, further vintage racing history followed by appearances as the star car in two academy-award wining films. The milky tea was Earl Grey, btw - but Ms. Padwell provided me with her phone number (however it has too many digits so I don't know)..."