On this side of the pond, 93 octane fuel is considered as premium, while 87 as regular and 89 as mid-grade. Why is there a considerable difference in the octane levels between your premium fuel and ours? I wonder if there's a noticeable difference in the performance/fuel economy as well.

 

Start with a new fuel filler cap. Cheapest option and I don't think you should get that much suction sound...

 

Already ordered!