blending being a part of it as our 94 is actually E10 (ethanol added to 91 which is ethanol free up here). We have temperature extremes that go -40°C (-40°F) to 35°C (95°F). That requires the fuel vaporization rate to be managed throughout the seasonal changes. In winter, they add a fair bit of butane to ensure good startup properties. However, that can start early in the fall and continue into the spring. Depending on when you fill up, that can play into the tune and dyno numbers.