That's some interesting data, ECO mode is worst than Normal and Sport mode. I know the ECO mode is highly dependent on the driver's driving methods and unless you feather the throttle, you are probably making the car work harder. I would like to know if you changed your driving style when on ECO mode? I would guess not, you seem to drive a whole lot and probably don't have the patience for that (I know I don't). Never the less, great info.I have just gotten thru my 3rd fillup in my CT200H. Each time the fuel gauge read about 1/8 full when I did the refill and the miles remaining was in the 40-60 mile range. Anyway driving on all 3 tanks was a combination of highway and city driving (20 miles to and from work dailey) and pleasure driving on the weekend for shopping and other errands. I will also say I did not drive with a lead foot when accelerating.
Tank 1: 398 Miles/8.99 Gal = 44.3 MPG Normal Mode Only
Tank 2: 395 Miles/9.12 Gal = 43.3 MPG Sport Mode Only
Tank 3: 376 Miles/8.81 Gal = 42.7 MPG Eco Mode Only
Started on my 4th tank and I plan on repeating this sequence once more.