HI
Again, 95RON is ok for the GOLF GTI, a knock sensor retards the timing preventing 'pinking'. You will loose a little BHP and Torque and thats it, MPG not really!!! VW tested the car to run on low sulpor fuel which we do not have (here in Ireland anyhow!! or 97RON come to think about it, well harder to get) but tested it on 95RON, They would not publish the spec as 95RON if it could not run on this fuel, end of story,, Running on 97Ron means of course better efficency and lower engine temps but it will run just as well, save a few quid on 95RON,,,No damage can happen to the engine as the ECU will detect the detenation (timing) and retard as nessary...
Any views, on this.. Cheers Focus RS owner for now but GTI on the way!! Ireland.