what is the fix for 07 prius trip computer miscalulations?

Yeah, take it back to the dealer.

Jeff

"Rocky" ...

Rocky, I have a Prius with a lot of miles on it now since January. It is best to use the gas gauge that is next to the speedometer instead of relying on miles driven for fillup timing.

The computer is really only there to give you relative MPGs, and is not really accurate all that much overall. It 'counts' how much gas is injected into the engine, relying on what the computer is telling it. Maybe it is right. I don't really think so, as my readings have compared both high and low a bit upon fillups. Even still, an MPG reading on only one fillup is flawed as well as the amount actually filled can vary as different pumps click off at different points and there is likely differing top-off parameters as well. A good MPG reading is one taken over about 5 tankfulls, all added together.

Are you mesmerized by that screen yet? Tomes

The trip computer is working fine. The gas gauge--also called the Guess Gauge--is crap.

Don't run the car out of gas. When it's down to a couple pips on the gauge, get gas.

The root of the problem is the flexible bladder inside the gas tank. It causes you to put more or less gas in at any given time, depending on outside air temperature. You can't gauge your mileage based on pump readings. Use the trip computer, or use the energy display with its mileage reading.

Because like so many Prius drivers, they think they need to play with their new toy. One way they play is by trying to see how many miles they can get out of a tank of gas. They do so by running the thing out of gas--unintentionally, of course.

God forbid they should just look at the built-in display that shows what their average MPG is for that tank. No no, they have to play and actually run it out of gas.

So many of them do this, it's hilarious. What's funnier is that they admit it in public.

(you may have to be a member of the group to view the poll question,but...) "On average, what is the difference between your mpg calculated by the car's computer and by the gas station fill-up method?

515 responses so far: Choices Votes % computer 5mpg or more higher 20 3 computer 4mpg higher 39 7 computer 3mpg higher 71 13 computer 2mpg higher 108 20 computer 1mpg higher 12 2 both methods about the same 136 26 computer 1mpg lower 5 0 computer 2mpg lower 9 1 computer 3mpg lower 16 3 computer 4mpg lower 4 0 computer 5mpg or more lower 7 1 varies too much to give meaningful average 88 17 "

My understanding of the displayed consumption screen MPG on the Prius: The amount of gasoline used is calculated by counting the number of "squirts" from one of the fuel injectors (and extrapolating for the rest of the fuel injectors to get gallons or liters, depending on market), and the distance is found by counting the number of wheel revolutions (to get miles or km depending on market).

As for how accurate the display is, it really depends on your vehicle. (see the above poll question.)

One or two tankfuls aren't really helpful, thanks to the shape- changing bladder tank found in the North American Prius. (Outside of the US with the standard metal tank, they don't have the wildly varying fillup problems.) You really have to average over several tankfulls. (Especially since you cannot be sure that the gas station pump's shutoff is going to happen at the same point all the time, anyways...)

For example, you can view graphs of my 2001 and 2004 Prius here (although I'm lagging in my last few fillups since I moved last year and rarely drive them anymore):

check the raw data link under the bar. You really need to do arolling average and not rely on any one tank's data.