Thanks! I was looking for that site, but couldn't remember the name.
I was talking to a guy down at the marina at the weekend, who had bought some of their "NOx Enhanced Petrol" and reckoned that it was wicked. A fiver a litre seems a bit steep though.
Anyone know if a Mini would run on the "Ultra Low Cost Value Unleaded (50 RON)" stuff? At 20p a litre, it's got to be worth a try.