As you probably know, outside of North America the Prius doesn't have the flexible gas tank bladder and this makes fill volume and the fuel gauge considerably more consistent. Despite this the fuel gauge still used to mystify me with it's apparent non-linearity (the first half of the tank always going way more km than the last half). Lately though I've come to the realization that if I "imagine" that there are twelve pips instead of 10 then my fuel gauge actually works almost perfectly. So when I fill up there are 12 pips, but the top two are "invisible". So for this reason it will stay with 10 pips showing for quite a long time, and when it eventually does drop to 9 pips then it's actually used 3 pips already and not just one as you'd expect. So now I find when I calculate my mileage at each "pip drop" using this method it's nearly always exactly what would be expected based on my MPG figures. Sorry that I don't know how applicable this discovery is to the US model, but personally I'm just glad that I've finally figured out my own fuel gauge.
It's engineered that way to fool us common folks. I put another 1.5 gallons of gas in my 2010 after the first click. I was able to drive 180 miles before the first bib disappeared. Now that I've added an Enginer PHEV kit, I've gone 300 miles before the first bib disappeared. In my Tacoma, that's 1 tank of gas. The Gas Gauge Says Full, But That's Not Quite True : NPR
Are all Prius's built in Japan and exported? Im wondering if they contract build them in any other countries {Usa-Mexico-Canada?} Is there a way to tell where your Prius was originally imported to or should i say exported to?
The gauge accounts for what it can see in the tank. No fuel level sender can sense gas to the very top of the tank. Additionally, when you fill the tank until the pump 'clicks' off, many times the actual amount of fuel in the tank is likely the full tank plus a little more going slightly up the filler neck. (That's why you shouldn't fill it more than first click - any more and you risk having raw gas get into the vent tube close to the top of the tube and in to the canister. Saturated canisters is a fairly expensive part to replace). The reason why a gauge shows no movement initially is that the fuel level in the tank has to run down until the sensor can actually see any drop in level. In a car like a Prius, that takes a little longer because of the efficiency (it takes a little while to use up that extra fuel the sender can't see). The less efficient the car/truck - especially guzzlers, the more the 'action' will appear more consistent as it will take less driving time for the fuel to reach the point where the sender will actually see any change in level.
I get 54 MPG and the first pip goes off about about 250 to 270 miles, so pretty much exactly equivalent to 3 pips instead of one. Yes I usually fill just until the pump first clicks off. It's not very difficult to get a consistent fill volume without the bladder. But the other thing about considering there to be two "imaginary" top pips is that it means that each pip is worth only 1/12th of a tank instead of 1/10th. Once I started considering them like this (only 1/12th each) then suddenly the fuel gauge made perfect sense and it honestly is quite accurate!
i have never owned a car (and i have gone thru more than a few!!) that had a "linear" gas tank. the top and bottom always represent much more gas than the middle... like, so ok. oh well. but that is because we filled gas tanks beyond the recommended levels and ran them down below the recommended levels...ya, thats right!! batteries are not the only thing that have a recommended usage range
Though my sample set is smaller, I've seen the same thing. As in most consumer product design, the conflict between 'accurate' and 'cheap' is nearly always settled in the direction of 'cheap'. I'm actually quite happy with the linearity of my Prius's gauge, it is a marked improvement. The previous car had only quarter tank marks, and my mental tick-to-tick 'calibration,' starting above the top, was for 40, 60, 45, 90, and 65 miles at 'normal' mpg. Another had only three marks (empty, half, full), but it went about 100 miles before dropping to 'full'. The low fuel idiot light served as an additional calibrated point.
Dave, the frustrating part is that the car knows how much fuel is in the tank. The miles to empty reading uses the same fuel sender in the gas tank and compensates for the senders non-linearity. If only they would send a linear gauge vs fuel remaining signal to the fuel level gauge.
Actually, 11.5, the last solid pip lasts about 1/2 or 2/3 of every other one assuming identical efficiency throughout the tank
Yeah that's right. I take the amount from the when I get the last pip until it starts flashing as 1/2 a pip. So twelve pips but I only use 11.5 of them. And that's the surprise, I'm now finding the gauge surprisingly accurate and linear since I started picturing it this way. This is of course without the tank bladder.
