Anyway as I tapped earlier - are we focussing on long lived cars - that last a long time in use, or long lived cars that last a long time in production, or is it a focus on simpler cars ?
There are quite a few models out of production which can more or less be built at home from the shell upwards including the Mini, 2CV, Renault 4, Austin 7, old Land Rovers, new Land Rovers
and the Model T - there is a place in the UK (can't find the link just now) that builds them from newly made chassis.
Its a thought - own the same car for life, replace anything from service parts to the whole shell when they fall apart