I have a 2011 Prius III. When I fill the gas tank it shows ten pips. The tank is 11.9 gallons so each pip represents 1.19 gallons. Iâ€™m manually calculating my gas mileage to compare it to the mpg consumption gauge. The first pip disappeared this morning at 49.4 miles. The consumption gauge says 46.8 mpg for those 49.4 miles. The manual calculation comes to 41.5 mpg. I know itâ€™s a small sample size and Iâ€™m going to keep monitoring it. Is the mpg consumption gauge accurate?