[msej449]

I use shell V-Power Nitro+ 97 or BP Ultimate 97 here in the UK, mainly because of the additives rather than performance/MPG. For my M235i, filling-up with a bit still in the tank (say 50 litres or about 13.2 US Gallons) costs US $73, compared to $63 for the cheapest, plain supermarket 95 (=US 91) with no additives. As others have opined, a $10 a fill-up premium for a car I'm likely to keep for a while, and which cost me around $48K is part of the overall cost of ownership.