6 Gallons only 3 bars down on the Gas Gauge??? (How accurate is it)

[pakitt]

Today I got the gauge to the blinking mark, drove until the range was saying around 10km - I filled up and only 36.5L went in.... the max is 45L, so what? it started beeping when in the tank where still 10-2L? what??? not very accurate...

[fuzzy1]

Originally Posted by pakitt

Today I got the gauge to the blinking mark, drove until the range was saying around 10km - I filled up and only 36.5L went in.... the max is 45L, so what? it started beeping when in the tank where still 10-2L? what??? not very accurate...

Have any of your previous cars been any more accurate?

Mine haven't. But I very strongly suspect that many new Prius owners did not pay any attention to fuel gauge inaccuracy in their previous cars.

[pakitt]

My previous car was a Polo - I would fuel every time the beep of the tank would light up and I was getting about 0-10km range on the board computer. I fueled consistently in this way about 40L out of 45L in the tank. That is, the range was going to 0km, but the tank always had 5L left (as per VW manual).
I was not expecting the Prius to tell me that I have 0km range and then be able to fuel 36L instead of 40L. But, I think, my Polo running on Diesel, has no vapour recovery system (diesel does not evaporate so easily at all) and the tank was simply a "tank" with no bladder.
But if the "tanking" process is so inaccurate, then there is no way to really determine whether the mileage is accurate over a few tanks. I think one has to average over many full fill-ups to even out the errors (tank with bladder, vapours recuperation, shut-off at the gas nozzle, etc.).
And as a rule of thumb, fill up as soon as it starts blinking - not because you are going to run up dry in 2 km, but simply because maybe you get consistent full fill-ups at the pump. This will take some time, I fuel up typically once a month, if I do only commute and not additional trips (which didn't happen in the last 20 days... ).

[fuzzy1]

The 2010 Prius has no bladder, at least in the U.S. market, so that shouldn't be an error source any more. As long as the top of the tank is reasonably consistent, you should be able to determine reasonably accurate fuel mileage for every tank. So far, after more than two dozen 'tankings', I am seeing few discrepancies.

On my previous cars (U.S. market), all but one had 8 to 17 liters of fuel remaining when the gauge needle was solidly at 'E' (Empty). The one exception actually ran dry with the needle above E. Compared against this experience, my new Prius is behaving well within expectations.

[Shawn Clark]

Originally Posted by fuzzy1

Have any of your previous cars been any more accurate?

Mine haven't. But I very strongly suspect that many new Prius owners did not pay any attention to fuel gauge inaccuracy in their previous cars.

All of my previous vehicles have been an order of magnitude more accurate. Never had a problem with fuel gauge inaccuracy in any previous car with a working sender. The GII has been an experience in that regard...there are problems with both accuracy and more importantly, a completely unnecessary lack of precision in the digital gauge.

It's not the owners' at fault, it is the bladder and the poor digital gauge design that are responsible for most of the trouble.

[fuzzy1]

Originally Posted by Shawn Clark

All of my previous vehicles have been an order of magnitude more accurate. ...
It's not the owners' at fault, it is the bladder ...

Pakitt's 2010 has a bladder? So the German models have different fuel tanks than the US models?

[Shawn Clark]

Repeating: All of my previous vehicles have been an order of magnitude more accurate.

I'm speaking of the GII's. This is the forum for them. And the digital fuel indication in the GII's is a detriment whether or not there is a bladder.

As to 2010's, I don't know if they have fuel gauge issues. From some reports I've seen, they do seem to share some venting issues that plague the GII's, despite the absence of the bladder. This is another "feature" I've never had in any other vehicle.

[uart]

Hi Shawn. Now that I've put several full tanks of fuel through I'm slowly getting used to the gauge. I think the lack of the bladder here makes it somewhat better. The main nonlinearity for me is just on the first (top) pip of the gauge, it's equivalent to about three of the others. I get about 250km on the first pip and then, while not totally linear, it's reasonably consistent at about 80km per pip after that.

So far I've run it down to the last pip three times, two blinking and one still solid. The fill volumes were (approx) :

1. 41L (last pip still solid)
2. 42.5L (last pip just started blinking)
3. 43.5L (drove approx 15km after last pip started blinking)

That's on a nominally 45L tank with no bladder, so it all seem pretty consistent.

[Acre]

My 2010 also seems to have a "guess gauge." Had me worried as it showed more gas being used than was the case. Temperature affects things to a degree as well; I've gained a pip after 20 miles of driving due I presume to warming. The issues is as descried here - lots of miles to loose the first pip, than rapid loss of subsequent pips.

[tsunami]

Originally Posted by uart

Hey you like living dangerously then. But seriously it's not good for the car to run the tank dry. If there's any crud that's settled in the bottom of the tank then you're going to suck it up and block a filter or something.

That makes no sense. The fuel is always drawn from the low point in the tank, not the high point so if there is any trash in the tank it will be sucked in whether the tank is full or empty.

Kirk