My car likes 91 octane or higher. I normally save money by blending 87 octane with 93 octane at the pump. It would be nice if the fuel-up page allowed for addition of two quantities and prices to avoid me having to do math or enter two fuel-ups :-)
Sorry, this is one of those "only a handful of people do this" requests. When we consider new features we have to think about how many people will use it and if that addition will make things more or less confusing for everyone by adding it.
You might look into ways to make that math easier for you to do. Maybe you could write up a special calculator that helps you combine the two into a single fuel-up that you then add via import.