2 pips & got 380 miles

Mapping pips to gallons is not an exact science, there is a reason it is called the guess gauge.

You may have used 8.5 to 9 gallons. 42 to 45 MPG?

 

49.5. fill er up and let us know! closest guess wins something?

 

It varies.

The outer shell is 11.9 gallons, but in North America there is an inner rubber 'bladder' that minimizes gas vapors. It is very sensitive to temperature, at 105 F it is over 11.5 gallons, at 32 F closer to 9 gallons. so even if the gas gauge was perfect, the tank around it changes size with temperature. Some owners find that their bladder folds to reduce capacity, other find that theirs restricts the speed they can fill up.

Mine is benign, with the anomaly that I can fill it up more in the afternoon than first thing in the morning.

 

For the US model with the fuel bladder, pick a number between 6 and 12. There in is the problem with your methodology.

Trust the displayed MPG until you can prove it wrong by systematic tank calculations. Log miles and gallons of several tanks full.

 

Long term record keeping has shown the the GenII MFD MPG display is approx. 2% optimistic compared to manual calculation (miles driven divided by gallons pumped). From tank to tank you may observe wide swings in error due to the bladder described above but after years or record keeping, owners have agreed on the 2% average error. The GenIII appears to be between 4% and 7% optimistic so far.

 

Yep. Ditto on all of the answers here.

When I lived in WA state and had very short drives in cold weather, I'd be lucky to get much above 40 mpg, assuming I even break 40 mpg. I'd have tanks where I'm down to 3 or 2 pips and haven't gone 300 miles...

 

As F8L stated, you will see very large swings on your manual calculations due to the bladder and guess gauge. Sometimes the MFD will be way higher. At other times, it'll be the other way around. If you care, you should average out the results (from both) over many tanks over time. You'll see they're both pretty close, when averaged out.

As for if it's full, well, there's http://priuschat.com/forums/other-cars/94001-gas-gauge-says-full-but-thats-not-quite-true-npr.html, but it's a Ford engineer talking.

 

If your mother in law is in the car, get gas at 3 pips, you will never hear the end of it if you run out.

With loved ones in the car, get gas at two pips, it is scarey by the side of the road.

Alone get gas at one pip, no need to run on fumes, it is bad for the fuel pump.

If the pip starts blinking, get gas RIGHT NOW, trust me on this. I ran out 7 miles after it started blinking one cold day,

 

Yep the displayed MPG is usually fairly accurate, some people have observed it to be about 2% optimistic, but that's still pretty good.

The per tank manually calculated MPG can vary considerably due to temperature induced difference in the bladder's flexibility and due to differences in exactly where the gas pump cuts out. The Australian model Prius doesn't have the tank bladder, so my manual tank calculations usually agree very well with the MFD displayed ones.

 

In warm weather I will get about that mileage at 2 pips. hot weather I'll get about 420 miles at 2 pips. Cold weather I'll get about 340 miles at 2 pips. I think you are doing pretty good. I hate the rubber bladder, because the gas gauge is never accurate. I try and get gas from Costco which is the cheapest place to get it usually about $0.40 to $0.50 cents less than other stations that are on my route from home to work. Since the gas gauge is so haphazard, sometimes I get gas from Costco when I really think I need to and end up pumping 4 gallons. Other times I think I'm good and then all of a sudden the pips drop rapidly and I end up spending more money on gas in the emergency.

 

What do you mean "the gas gauge is never accurate?" the gauge is indeed pretty accurate. It's your guessing and reliance on a specific number of miles per tank that is not accurate. If you disagree then I would suggest having your car checked out to ensure the sensor is within manufacture specs.

I've never had the fuel light come then only be able to pump 4ga. I've always been one of the people who rarely fit more than 8 or 9 gallons into the tank even after running on the low fuel light for awhile. So I find it odd that you could only add 4ga after reaching 2 pips. if this is not an exaggeration I would definitely have the car checked out. You shouldn't have to deal with such inaccuracy. I could totally sympathize with such an issue.

 

keep refilling and tracking your total miles and total gas added. divide total miles driven by total gallons added. the more you do this, the more accurate your average mpg's will be.

 

New 2008 owner here, I am learning. Ran out of gas on the first tank I full. I was trying to get back to my town before I filled up, dumb idea. Drove 487 miles on probably 10 gallons, the display said I was averaging 48 miles per gallon so it was right. The PIP started blinking at 420 miles and one square showing. I thought since it holds 11.9 I theoretically should be able to go at least 135 miles and I was only 80 from home when it started blinking I read somewhere it starts blinking with 3 gallons left. I also read DON'T over fill it so when I filled it for this trip I only put in 1/3 of a gallon after the nozzle shut off, a total of 9.1 gallons.
I have concluded if you stop putting gas in when the nozzle stops (and that is what you want to do so the bladder and canister isn't damaged) you probably only have 10 gallons in the 11.9 gallon tank. Therefore "I state my name do solemnly swear to put gas in my wonderful Prius AS SOON AS THE LIGHT STARTS BLINKING" or before and not try to go another 67 miles.

 

Just out of interest, how far did you make it on the blinking pip? Did you make it 67 miles (out of 80 to home).

 

I made it 67 after it started blinking. I won't do that again too many here have said you just never know how far you can go. I think it has a lot to do with how much top it off after it stops. Which I think puts you at 10 gallons.