I have found that Eco mode eats the fuel on the open road, probably because you need to get away from junctions , roundabouts etc. Other users confirmed this. you are right, things like Air Con are suppressed and the ICE power is reduced. Some owners complained about poor mpg, and found when Eco mode is not used on the open road it improved. I think Eco Mode is better in traffic and around town because of the reduced power available from the ICE, and the way the hybrid system is set up for eco m