I Just got my Prius a week ago and was wondering how accurate the onboard computer is? According to the consumption screen I am averaging around 52 MPG. (it goes up and down but seems to stay between 52 and 53. I have put about 225 miles on the car since the last fill up and the gas gauge is showing 1/2 of a tank left. I heard you really can't go by what you put into it to find a true mpg because of the gas bladder. The car only has about 550 miles on it. With gas down the street at 3.75 per gallon I couldn't be happier if the car is getting anything near what the computer says. Jonathan
The computer is accurate. Most people doing long term manual calculations say that the MFD mileage is a bit optimistic, but within a mile or two per gallon. The computer uses fuel injector pulse timing to count the amount of fuel squirted into the engine, so it is very consistent as well as being accurate. Tom
I recently surpassed 10,000 miles. I've been keeping good records of all my tank fillups and have found that my MFD mileage has averaged 2.1mpg higher than the manually calculated mileage (recorded at GreenHybrid.com). 50.3 mpg per MFD, 48.2 mpg actual per manual calculation. Very consistent, too. In every fillup except one (oddly - the most recent one), the MFD was higher. At 10,000 miles, I changed to Mobil 1 synthetic oil, after 1 tank the MFD displayed 54.5mpg, and the manual calculated method resulted in 57.2 mpg. I think that's an anomaly and will eventually return to being lower than the MFD.
