Thanks @kezo Yes, I realised that the USA fuels (and ratings) are different. When I get the cars on test I’ve made a note to look inside the fuel flaps to see what the label states, but the U.K. owners manual for the X5 implies;
50e Super Unleaded E5 (RON 98) is best, but Unleaded E10 (RON 95) is OK.
M60i Super Plus – Shell V-Power (99 RON) best, but Super Unleaded E5 (RON 98) OK.
Diesels – Minimum Grade B10 but Optimal Grade B7