Yep, from what Barnacle says the ECU can't take advantage of higher octane it just retards ignition to prevent damage if your engine starts "pinking". So, in short - use standard fuel with a 16V(or VT).

I get easily 400 to a tank of V-power thats with a G-tec and k&n cone, cant get more than 330-50 to Tesco 99. Wifes 3.0 V6cdti vectra is the same she gets 500 on V-power diesel compared to 400 on tesco fuel. So is theres definetaly something working better with V-power

Ah well I'll have a good pint down there with the 3 squid I save

I once had lone of a Daewoo Nexia off my girlfriends parents which suffered terrible hesitation under acceleration, by mistake whilst filling up with petrol I realised I'd filled up with V-max but it cured the hesitation in an instance, the higher octane compensated for the fact it was suffering from some fuel starvation under heavy right foot.

A relative of mine found the same thing in a dull Corolla 1.6, it cured a pinking problem they had running with sainsburys fuel.

So it's not even worth using supermarket higher octane fuel? Just use standard Shell etc?

yup no point putting in expensive vpower or bt ultimate on a 16vt as it will have no benifits mine drank moore higher octane on a test i did 95 ron all the way,.... Why pay more