MPG displayed on Toyota Prius' Energy Consumption screen.
Both of my car pool partner and me have a Prius. His is 2005, mine is 2008. Later last week, he added gas before we drove home. When we arrived, the MPG on his car showed 53.1. I added gas in the same gas station before going home yesterday. But when we arrived, the MPG on my car showed 48.3. I am not sure is the new model less efficient or Toyota used different calculation now. Also, as for the last 30 minutes MPG for my drive (it took us about 30 minutes to get home), 5 of those 6 bars were over 50, 2 of them were over 75. Only 1 bar was a little bit blow 50. And there were not a lot of traffic light stops (the roads are not crowded at all in the suburb of Pittsburgh). If the MPG shown on the screen is for this tank of gas, this 30 minute drive was about all I had for this tank of gas. Mathematically, the number 48.3 doesn't make sense. What did I miss? Thanks.
Unfortunately the bars in the consumption screen reflect mpg's over time. This display is really more to show you the trend of your WHOLE trip. For instance what are the geographical locations like hills that impact your mpg's. Keep in mind that many different factors influence your overall mpg including: tire pressure; keep those puppies up, max pressure for mine are 45 and I try to keep all four around 40. A/C; although with models 07 and later the A/C compressor is run by and electric motor NOT the drive belt on the combustion engine, having said this drawing more electric current depletes the battery and the engine will run more often (I am not sure if the heater is electric or uses hot water from the engine like in conventional cars, either way more use = more gas). Radio and Headlights again any electric components drawing current will lower mpg. The most important thing to keep in mind is that 1.7 mpg's is not a HUGE difference and the more you drive your prius the better you get at keeping the vehicle under battery power and not engine power. My wife can drive the same route as me and will get up to 5 mpgs less because I have more practice.
My husband and I used to have a contest as to who could get the best MPG on our Pius. He always won because he used the "B shift" (breaking) whenever decelerating. He could bump the MPG up to 55!