Fuel Refill vs Display...

Hi Chris,
I usually fill up and than go one more click. Than stop.
The MFD and my hand method differ less than 1 MPG.
Hope This helps.

 

The individual stores can set the rate at which gas flows from the pump. I would try to find a gas station that pumped slow to medium. There are two gas stations close to my home. One will pump the gas so fast it shoots gas out at me sometimes after the click. The other station pumps gas so slow I become impatient. I have not used the "hyper pump" station since I purchased my Prius.

50.2 vs 37 seems to be way off. In my experience is the MFD will be within +/- 1MPG using my calculations according to the pump measures.

How many total gallons were you able to place in your first fill up?

 

Results after 1st fill :

MFD : 42.6
Calc : 40.3

 

I haven't tried the train the bladder game. Looking around PC it doesn't seem to make a difference. According to most PC members it is based more on outside temps.

Toyota should have this issue better documented. I was hoping to use at least 11 of the 11.9 listed gallons and go nearly 600 miles before fills. No dice. The most I have put in my tank is 9 gallons. Of course I have not let the last PIP blink yet either.

 

You can still squeeze 600 miles out of a tank. I've managed a few. This summer I hope I can squeeze out at least one 700 mile / 70 MPG tank.

 

I'm very new here, so excuse me for just jumping in. I have owned my 07 Prius since last September. Then took it to Florida with me this Christmas. I have gone from warm to cold to warm weather and will tell you that temp has a LOT to do with it (mileage as well as gas tank capacity). In colder weather the tank will not come close to holding a full tank. To offset I can keep clicking away past "full," and still have the gas gauge show less than full.

It seems to me that calculating mileage is a very tricky issue with a Prius. This is true for 2 reasons: 1.) No one really knows exactly how much gas is left in the tank when you fill. So, fill-to-fill calculations are sketchy at best. I have always trusted my display and traveling the same distance and route to work and back have seen my #'s fluctuate wildly based on (92 miles each way on an interstate highway): road grade, temperature, wind speed and direction (a big one). I have gotten as low as 36.9 and as high as 52.6.

I have NEVER gotten close to 600 miles on a tank.

 

By squeeze due you mean a blinking PIP? If not I cant wait to see what MPG I get in August when it sometimes 107 F in the shade.

 

2000 miles into a 2008 prius, and I have done mpg checks at fill-up 4 times...and calculating 43-44 mpg...which is consistent with EPA results. MFD generally states 47-48 mpg range, almost 10% higher...I must believe calculating it the old fashioned way is more accurate.

As a side note, my 2004 Sienna has an LCD mpg display, which typically runs ~10% higher than manually calculating it, and they may very well have the same MPG calculating system...

 

Calculating manually is only accurate when calculating several tanks, there is no way to be sure you added the exact same amount of gas that was used.
For example say you calculated 4 tanks at once. With the 4 fill ups you added a total of lets just say 35 gallons and travelled 1800 miles. you would have about 51 MPG hand calculation. But if it is warmer outside then your last fill and you only calculated a single tank (most likely added an extra gallon) say you only got 425 miles and then added 9 gallons this time, a computer display of say 53MPG now becomes a 47MPG hand calculation because of the extra gallon you were able to fill this time.

 

Huh??? Your going to have to show me some hard data to convince me the density of gasoline vaires by more than about 1% in normal temp swings...

edit - just verified it would take an 18 F change to cause a 1% change is gasoline density. And keep in mind, this is not in ambient temperature, but in the temp of a large mass of an underground liquid reservoir. So except in the most unusual temperatures variation over fill-ups that were widely spaces, temperature will not affect the gasoline density in a measurable way...

So can someone try again to tell me what I dont understand?

 

Here is the easiest way to explain it. The Prius has a bladder inside the fuel tank, it is able to stretch more when its hot and less when its cold. Meaning that the size of the gas tank varies from fill to fill. Do a search here for "bladder" and then you will understand.