Thanks to everyone for your helpful replies.
I think searching Le Bon Coin for a car has been similar to finding a house-though not as bad. I've read the Which guide to used cars & mostly they're great until over 3 years old when they develop lots of expensive-sounding faults.
The dilemma has been should we get an old cheap one & take a chance on it breaking down leaving us stuck in our new house in its tiny commune-probably ring the church bells for help! OR buying a flashier ? more reliable, more expensive one that folks in supermarkets everywhere will park too close to thereby scratching or bumping 'my precious'!
Think I've found the one-like the house a compromise-can't wait to get in it-our 'own' shower for the first time since September 2014 AND a double bed at floor-level as opposed to the Hymer raised bed. Really fancy test-driving the new to us car-it's the same brand we had in UK that was super-reliable for us.
Thanks again for all the useful information.
All the best,