Just filled up on my first full tank (I first filled up at 177 miles) and using ODO got 42.66 mpg. Car MPG tank gauge said 45.1, so mine is optimistic just like many others have reported.508.9 miles used 11.93 gal. Used same pump and used the fill it until it almost goes on the ground method, very full. This tank was about 65% hwy. and 35% town. If I factored in the 3% ODO error (which I checked against 2 different GPS's), it would be 43.94mpg, but I feel to compare with other reports, I should just use the ODO uncorrected reading. I varied speed on highway since it is a new car. I also probably drove it a little easier than I will normally, but I'm still learning the hybrid system as this is my first hybrid.