[Peter K_B]

In some countries, premium is at a higher octane than 91.

Here in Canada, some Petro Canada stations sell Ultra 94 with higher octane. (I have seen some forum posts on the Web claiming that BMW cars are not intended for use with such octane unless specially tuned. I have no idea if that is correct.)

Some articles about performance cars suggest using gasoline with no ethanol at all. But in North America nearly all gas has up to 10%; and BMW says that is ok. In Canada and in the USA, Shell sells a 91 octane gasoline V-Power Nitro+. In Canada, it contains zero ethanol but not sure that is the case in the USA.

I got the Dinan Tune Stage 1 installed and the specs they publish indicate the hp and torque with 93 octane gasoline. So, my M235i should work well with Ultra 94 gas. When I cannot find it, I look for a Shell station and then I use the (91 octane) Shell V-Power Nitro+. Is this based on proven facts? Not really.