FWIW, I've found that, while it might be easier to get better efficiency in one of the Eco modes, you can achieve most of it while in comfort mode, it just takes a little more concentration and restraint, and, possibly comfort since HVAC does use power that's automatically limited when in an Eco mode. Unless you really need to save a bit of energy, the tradeoff in comfort and fun may not be worth the cost. I think the i3 was optimized in comfort mode, and the eco modes were added as a potential necessity, if you really needed a bit more range. They do work. The newer versions with larger batteries make those modes less important for most. If I wanted a more compromising vehicle, I might have bought a Leaf.