Just seen this on the news affecting hundreds of cars, mainly Tesco and Morrisons petrol. Apparently it affects the Lamda Sensor and brings your car to a juddering halt. Stick to Optimax for the time being, it seems to be safe. I filled up with it on Sunday, no problems so far.

 

they are saying possible Ethanol contamination.. but that appears to have been ruled out as the AA can't find the issue.. seems lots of people re having sensor problems an garages seeing a raise in issues with cars in this area...