Im quite flattered really that I stirred up all this fuss.
Anyway, thanks a lot to everyone for all the advice - especially Final_Maxim who seemed to show a lot of restraint in not getting caught up in the whole thorny topic of speeding! hehehe
I think its time to have another look under the bonnet to check that everythings as it should be.
If I dont find anything wrong (which is very likely seeing as I know little about what goes on in there - something to do with horses im told) then ill take it back to Renault and take one of their guys onto a windy motorway...
Ill post the outcome of all this, but dont hold your breath coz I think itll be a good few weeks till its sorted.
Kot