I always try and avoid parking fines or getting flashed when abroad as you just don't know when it might turn round and bite you. Should you get stopped by the police, say, and they find a number of unsettled speeding offences on their computer for your registration number, I would imagine that things could turn difficult.
The other thing worth remembering about driving in France is that being caught exceeding the speed limit by more than 30 km/h will lead to your licence being taken away from you on the spot (even if you're foreign - I know somebody this has happened to. He then had to return home on public transport and have his Ducati shipped home at vast expense). In extreme cases of speeding the police also have powers to impound and sell off or crush your vehicle.
