I've also found my mpg improves on highway - depending on speed! If I keep it within the 60 mph range, I can get at or above the 49 mpg highway EPA rating. Pushing speed to 70+ I can see in the 'immediate mpg' gauge and average mpg total the loss in fuel efficiency.Have only had my Insight for the last month. Not sure what others experience is but for myself, when driving on the highway the vehicle drives better and gets better milage. Does better on hills also....... The drone from the engine is far less pronounced.
Hills are still tough going at city speeds though, unless I anticipate them with momentum built up by accelerating before the hill, OR unless I switch to Sport mode. Do you do most of your hill-driving in city or highway conditions?
Most of my hills are semi rural........ So speeds are around 80kph.