It's a lifetime work...
I started 12\15 years ago with an old McIntosh and it was just a small list of sportscars.
The PC crashed many times and each time I started again with some improvements.
At the end I decided to list each and every car, production, kit cars, racer, tuned, custom, buggies, retro, replicas, and so on.
It is a sort of index of all the cars featured in all the books, encyclopedia and magazines I have...that's why if someone asks me for a pic of a Fiat 1100 by Savio, I just have to look in my index, see how many sources I have with that car and post the pictures or info.
In this form it is not very useful, because the greatest feature of it is the source of the info: beside the De Lorean DMC12, for example, there is a list of 8 books, 3 encyclopedias and different magazines where I can look for info or pictures.
Another big work I did was to build back the story of a brand: I can summarize in few minutes all the relationship between Sunbeam, Talbot, Darraq, Simca, Talbot-Lago, Matra...or the merges of all the British brands, just looking in this file.