Can someone look at this and comment? thanks!

Notice that your AVG MPH computed from the trip summary does not equal your AVG MPH shown on the trip odometer. The trip summary shows an AVG MPH of 40.8 which is lower than 42 MPH shown on your trip odometer which indicates that you reset your trip odometer after you started the car. Your ICE must have been on at the time when you reset the trip odometer. Thus the MPG is slightly different.

 

21.1miles/31minutes*60=40.8mph average speed.

 

the lower one because you were burning fuel without moving, as hybrid bear said.

 

It depends on what you're looking for. None of the displays are accurate in that manually computed mpg will always differ, but the displays are useful for determining if something may be going wrong and needs attention, etc.

The Ending Screen, as you call it, is useful for the time the car was running, but only for that particular trip. It gets reset for the next time and generally has no real bearing on what your overall mileage will be unless your driving is all the same.

The Trip A (or B) meter is useful if you use it to track fuel usage between individual fill-ups. It is more useful in predicting what kind of mileage you can expect over time because it measures a longer period and averages mpg over different terrains, speeds, loads, etc.

The other Trip meter is useful if you use it to track fuel usage between multiple fill-ups, like a complete trip, or until it reaches 9999 because it uses even more data.

Manual calculations based on miles driven and fuel pumped are most the accurate for the average driver, especially if they are recorded and averaged over time. They still aren't totally accurate because of pump variances and many other factors, but they are as close you can get without resorting to special techniques, like topping off the tank (which could damage emissions equipment).

 

The 57.3 mpg is measured from the time the trip meter was reset. The 55.7 mpg is measured from the time the car was started until it was shut off. The assumption is that you started the car and the engine ran for some period of time (if only seconds) before you reset the trip meter. If that was indeed the case, then there was fuel burned during that short period. Neither is more accurate than the other because both show different circumstances. FWIW, 21 miles is simply not enough distance or enough time to determine what you estimated long term mileage will be (see my other post). If you reset the trip meter while the car was in ACC mode (engine not running) and then you started the car and drove the 21 miles, they should be pretty close to each other. I wont say they'll match exactly because I don't know all the variables being used by computer.

 

By doing so, it didn't count the fuel that was used before it was reset. According to the numbers, 0.515 gallons of fuel was used to go the 21.1 miles. However, because you reset Trip B AFTER the engine had run a few seconds, Trip B only counted 0.500 gallons of fuel. The missing .015 gallons is miniscule in the big scheme of things, but trying to determine expected long-term mpg using a 21.1 mile trip simply does not provide enough data to be of much value. Had you gone 100 miles without turning the car off or idling, the values would have been much closer because the .015 gallons would have not have the same impact on the calculations. However, even that number would have been an estimate ONLY for that type of driving. If it had been all highway at 55 mph, you would have gotten one number. But if it was stop and go in the city, you would have gotten a completely different number.

 

i'm sorry, i meant the lower of the mpg's, not the screen shots.

 

If I am following the story right the discrepancy might be explained by a different battery SOC when the trip meter is zeroed.

 

Remember during high school math class when everyone said: "When the hell am I ever going to use this crap?"

When you buy a prius, that's when.