I'd been running mine on Ultimate for nearly a year on Ultimate and when the prices went over £1.10 i couldnt be bothered with it. Filled up with
Sainsbury's City diesel and I was shocked how much the car played up! You could feel the whole car juddering on tick over - literally feel the car moving with the tickover of the engine!
Plus the pump clicked out several times to say my tank was full. Got in the car and it was 3/4 full! It must have frothed up or something!
Needless to say - back on Ultimate or Shell Optimax!