142MPG? I need some help here.

[David Beale]

I doubt the pump accuracy changes much due to flow rate. The meter is a displacement type, and the fuel doesn't bubble until it drops out of the nossle (unless the underground tank is almost empty). The main reason for refilling slowly is to get a bit more fuel in before shutoff, and to avoid a lot of bubbles in the tank that have to "bleed off", possibly causing a burp out.

Always remove the nossle slowly, just in case. I even depress the nossle down to create a gap in the seal at the top to bleed off any pressure that -may- spit out fuel. If you find yourself in this situation (fuel trying to spit out), be patient. The pressure can be bled off slowly without much fuel loss. Pearl has only spit on me twice, both times due to a faulty filler shutoff. The -second time- (yes, I learn from my experiences) I avoided fuel spillage by being patient.

Be aware you can't use the last gallon or so of fuel in the tank. Unless you are shaking the tank. There is a cavity in the tank system where the fuel pump resides (for cooling and to ensure it is always pumping fuel and not air). Contaminants also settle out there (below the pump). Also note, it -may- be possible to overheat the fuel pump by running out of fuel, though the fuel pump in the Prius will shut off if the engine dies, so it is a little less possible to burn out the fuel pump in a Prius than in other cars.
This cavity also causes what some owners who have run out report - you have to put in at least two gallons to get the thing running again.

Running out of fuel in a Prius is not a "good thing" (tm). Better to avoid that situation. I fill up at around 1/2 tank if in the city. On the highway I fill up at 1/4 tank if possible. Besides, it's fun to fill up the Prius. Perhaps because my previous vehicle was a Nissan Pathfinder (the anti-Prius), which took 80 litres of Premium! Around $100!! Pearl usually takes $20 to $30 of regular.

[Ct. Ken V]

Hey, all,

I always fill up when I get to only 2 pips remain'g (once it got down to one pip before I could find an open station---I didn't like that feel'g). I have an '05 that automatically resets BOTH the MPG & miles-between-fillups on the screen ('04's do that too). In the winter I go between 350 & 380 miles before the 2 pips. In the summer it goes up to between 400 & 430 miles before getting down to the 2 pips.

I think on the '06 though '08 models only the screen miles get automatically reset at fillup because the MPG is left alone each time to maintain a "lifetime average MPG" (a throwback to the way the early adopters preferred it in their '01 through '03 models).

My point is this : either fill up at 2 pips all the time (to be safe) or if you're going to do the calculations of MPG times the # of useable gallons you feel comfortable with (because of the bladder, more in the summer & less in the winter), then give up on your lifetime MPG (keep your own records on a pc spreadsheet) & do a manual reset (of the MPG) at every fill'g.

My reason'g is this : on an '06 through '08 car (lifetime MPG) with many miles on it, the lifetime average will probably be pretty high. So unless you reset your MPG at every fill'g, one tank that gets affected by an extreme drop in temp or new hilly terrain won't show too much of a drop on a lifetime average display but will certainly reduce the # of miles you can safely travel without running out of gas.

Let me use an example. Let's say your lifetime average indicates 52 MPG (lucky you) & you don't ever reset your MPG's on the screen. Let's also say that it's warm weather, but you haven't really noticed that on this tank you've been doing a lot more stop & go (read that "warm up") cycles & you've also been in some hilly terrain. If you HAD reset at the start of this tank, you might find your MPG for THIS tank to be only 40 MPG. If you HAVEN'T done a reset then this one "bad" tank might only bring your lifetime MPG down from the 52 to an indicated 50 MPG. That would mean a difference or "error" of 10 MPG [indicated 50, LIFETIME minus REAL 40, on this tank only (WITH the reset)], times 10 useable gallons (you're think'g the 10 gals because it's warm weather, remember). These calculations would lead to 100 miles less of useable travel than you think you safely have.

That's why I'm glad my 2005 automatically resets BOTH MPG & MILES at each fillup. I just look at my true MPG (from the car's own calculations of fuel actually put through the injectors) & I can pull out my logbook of how many gallons I added at last fillup & multiply those gallons times my MPG & fillup before my miles on screen reaches my calculated "safe" miles. It's fairly simple to do but mostly I just refill at 2 pips & it's within the ranges I stated above in the 1st paragraph. I've never run out of gas yet & I don't intend to.

Also, you should go to the main forum & find the thread entitled "When do you refill?". It's a poll, so vote, view the results, & then read all the comments there. See other like topics or threads (usually found way down at the very bottom of the page).

Ken (in Bolton,Ct)

[Genoz World]

THIS brings up an interesting point. my FIRST pip disappears at about 60 miles driven. My computer says my mileage is about 46-47 mpg.

is this normal? i was not too concerned about this until i read this thread.

thanks for any input,

[Patrick Wong]

Originally Posted by Genoz World

THIS brings up an interesting point. my FIRST pip disappears at about 60 miles driven. My computer says my mileage is about 46-47 mpg.

is this normal?

The point at which your top fuel gauge segment disappears depends upon how full you make the tank. Some people can go 150 miles or more because they fill the tank way beyond the first pump click off.

Your car is "normal", given the variability caused by the bladder, production differences etc.

[DaveinOlyWA]

Originally Posted by Genoz World

THIS brings up an interesting point. my FIRST pip disappears at about 60 miles driven. My computer says my mileage is about 46-47 mpg.

is this normal? i was not too concerned about this until i read this thread.

thanks for any input,

you are normal, people getting significantly more than this are overfilling. in summer, you will notice getting 80-110 miles on the first pip, again, that is in the normal range. getting less than 80 in summer, is nothing to be alarmed at but getting significantly more than 110 miles should be addressed.

after 4 years, i can tell you, if you are stopping at the first click (or near it. you should always have an idea as to how much to put in based on your MFD display assuming you manually reset after every fillup) you will be in the normal range.

now there are too many people who want the 11.9 gallons in the tank. well, lets face it. we are all basing this want and need on previous vehicles we have owned. once again, american car manufacturers have come back to haunt us. i read many stories about disappointed Prius owners relating stories about how their gm had a 20 gallon tank and they were able to put 20+ gallons in it because of the "reserve" all the while discounting advances in technology on Toyota's part, the lack of quality control on gm's part, etc.

you cant have your cake and eat it too. Toyota's biggest mistake was reporting the tank size in the first place. their 2nd biggest mistake was assuming that we would be happy with a vehicle that had essentially the same usable range as our previous vehicle. (ya thats right, even when we have only 9-10 gallons of usable gas that still gets us the same distance as our previous car)

now maybe they should use a tool like my GPS system, it has a digital gauge for miles to turn, miles left in total trip, etc... when i am 1000 feet away from my turn, an analog gauge pops up so i can see the rate i am approaching the turn, makes it nearly impossible to miss a turn. now if Toyota were to incorporate something similar in their gas tank, maybe that will prevent people from ignoring the warnings to get gas. just have a mini analog gauge pop up when the last bar starts to blink...

[Genoz World]

thank you! i'll just nevermind this and keep driving.

safe driving and cheers.

[DaveinOlyWA]

another quick comment...the filler tube is exactly that, a tube used to fill the tank... its not a "storage" tube. so if you see gas in the tube, you are in the process of destroying your fuel storage system.

[jdonalds]

On a recent trip I noticed the gas gauge didn't drop one pip until I had driven over 180 miles after filling the tank. I think it's normal for the Prius.

jd

[qbee42]

Originally Posted by SpartanScott

I'm not sure if it's a proven fact, but it has been stated here on PC many times. The pump meters the volume flowing. Pumping fast will might cause turbulant flow so the pump would count air/bubbles/foam as gas volume. I'll let someone else back me up with facts here. I don't believe this can account for ani-gas's 5% error in his 5 gal test. His station is most likely messing with the pumps.

The pumps meter the same at slow or fast settings. The difference in flow is not enough to change the physics behind the operation. This advice is one of a whole bunch of urban legends involving gas stations and fueling.

Tom

[racerbob]

anti-gas,
Do you have bigger wheels/tires perhaps?