After experimenting with each mode, I generally just leave it in Smart mode now. While in Smart, it seems to run in Eco about 80% of the time and switch to Comfort when I’m going up a hill or coming from a stopped position, etc. The last two tanks of gas in Smart mode were 26.3 and 26.5 mpg average based on actual fill ups. The computer was telling me about 27.7 or something close to that figure.