I have a TCH, but I wanted to chime in. I'm always skeptical of any single tank MPG figures, because of the variation of the auto-shutoff on the previous and current fill-ups. (I do NOT advocate continuing to "squeeze" in more gas after the pump clicks off--you'll likely end up forcing some "extra" out the overflow and onto the ground.)

Anyway, back to my theory. Your last 2 tanks were calculated higher than the computer display showed because the pump's auto-shutoff tripped early. You therefore put in less fuel, giving you seemingly higher MPG. Now you're seeing lower MPG because there's no "free lunch". You put in less gas the last fill-up, so now you seem to be going through fuel faster.

I like to average 2 or 3 tanks together to get an idea of my fuel economy. I suggest you make sure your tires are properly inflated and just enjoy driving your new car. Eventually, you'll have enough tanks of gas to give you a more meaningful MPG figure. The best part is that you're beginning at the beginning of the warm weather, when you'll see higher MPG figures as compared to those who bought their hybrids during winter.

Best wishes.

B. Goodman