Lots of people say they only run the Scoobies on Optimax or Super Unleaded. is that purely for performance? I know Japanese ones need to run on richer fuel, as their ECU tells them so, but for UK specs, is it really necessary?

I felt that optimax made my car run a lot smoother and was more responsive....didn't give me any more boost though.

MY97 UK WAGON

Well, the Euro spec cars are set up for 98RON. They are/were sold in the UK for 95RON, as it's much harder to sell a car that only runs on SUL (or rather, above SUL :rolleyes:).
But the ECU will cope with NUL (95), the car just won't be as quick, will run rougher, etc. I think I'm not on my own in thinking it's worthwhile spending the little extra cash on SUL over NUL - seems a shame to not use it.
Most definately steer clear of supermarket stuff. It can be really quite iffy... for anyone who doesn't think it's a problem, watch your KnockLink after filling up with the stuff :eek: Even if the ECU can pull the timing back this much, the resulting performance would be appauling! I had no choice a while back but to use this stuff (had run out of octane booster too - d'oh! :)) and even driving like a nonce after seeing the KnockLink, the ECU had gone into 'panic mode' & I had 'actuator only' boost (ie almost none :)).

Don't generalise too much about supermarket fuel. There's nowt wrong with the Sainsburys SUL that's available round this neck of the woods ;)