Result: I ended up not considering anything less than three years old, and am still the content owner of an off-lease diesel 2008 Ford Focus Turnier (station wagon), about to have a new timing belt put in. My cost per kilometer would have been lower had I been confident in my manual shift driving capabilities (at the time, no; now, yes) and had eschewed luxuries like leather seats and the larger engine.

Cost per km over the past seven years: 0.334 EUR Average cost per year (not considering that I've dropped my driving from over 20T to under 8T km/yr): 5826 EUR

But I've not looked at it from an inventory perspective; it does spend an awful lot of time sitting in our garage ever since I switched offices and now carpool with a colleague who loves driving his BMW and is delighted that I give him 10 EUR/wk for gas and peer-pressure him into leaving for work at 7am :)

I'm basically trying to compare EVs, hybrids, and gas cars. It would be especially interesting to base data on historical TCO for various brands.