That's the beauty of a 3.7 Roadster. There is so much spare power available simply by exploring the upper rev ranges that any old petrol seems to work. My current favourite based on price alone (and as a Yorkshireman ) is Asda E10 unleaded.
Richard
2018 Roadster 3.7 1966 Land Rover S2a 88 2024 Royal Enfield Guerrilla 450 1945 Guzzi Airone
) is Asda E10 unleaded.