I have yet to use the ECO mode on my new Hybrid and I have just over 900 miles on it. As a matter of fact, I have just started to read the manual in depth and I was reading the part on the different modes that you can select and their function and starting today, I was planning to give the ECO mode a try while driving around town. From other owners perspective, have you noticed a fuel savings by using the ECO mode in the city and do you use it also on the highway? Do you lose any power and acceleration on the interstate, especially when getting on it from an on-ramp when in ECO mode? Any noticeable difference in the AC when in ECO mode? I suppose that I could answer some of these by experimenting myself, but I was just wondering what I can expect.