I thought I would report my first two tanks with my new 2011 Insight EX. On the first tank, provided by the dealer, I decided to drive like I had been driving with my former 2000 Saturn SL (traded in for this car). I also on this tank ran the car with AC blasting (It is hot here in Arkansas!) for 15 to 20 minutes while I played with all of the settings of my vehicle. Despite this, I got 43 mpg on the first tank, which had ~ 15% city driving. I did NOT use ECON mode.
On this second tank of gas, I used ECON mode and tried to pay a bit more attention to how I accelerated, etc., but not slavishly so. I also used cruise on most of my highway trips. This time I probably had ~ 25% city driving. This time I got 46 mpg for the average you see above.
Today I inflated my tires to 40 psi. They were at the Honda recommended 33 psi. I will see how this affects my mileage for the third tank of gas I started today.
So far I am very pleased with the vehicle. On similar drives with the old Saturn I would average 30 to 33 mpg; not bad, but it is nice to be doing even better!