I used it regularly in the scooby for two years and alternated with 95 unleaded too.... couldn't notice any difference at all... and that was in import, around 300bhp'ish that was supposedly best run on 97+ ron. There's certainly no difference in a clio I reckon, well not one that you can 'feel' anyway. There's been a few tests on this and its only turbo cars mainly that get any real gains from what I remember.... Maybe it is cleaner and more efficient but I reckon its more mind over matter when thinking it feels quicker.... certainly in a NA engine with sub 200bhp...