Prius gas gauge

[whereisz]

1 little square = 1 gallon?

[Rae Vynn]

<div class='quotetop'>QUOTE(whereisz @ Jul 10 2007, 06:49 PM) [snapback]476525[/snapback]</div>

1 little square = 1 gallon?
[/b]

Not exactly...
Around here, it is referred to as the 'Guess gauge'... and your guess is as good as mine what each little pip means!

[qbee42]

It's non linear. Most drivers find that the gauge sits at full for quite a while, then drops at a more or less predictable rate after that. It differs with temperature and appears to differ a bit from one Prius to the next. The moral of the story is to not trust it too much - just buy gas before it gets to low.

Tom

[whereisz]

<div class='quotetop'>QUOTE(qbee42 @ Jul 10 2007, 07:11 PM) [snapback]476542[/snapback]</div>

It's non linear. Most drivers find that the gauge sits at full for quite a while, then drops at a more or less predictable rate after that. It differs with temperature and appears to differ a bit from one Prius to the next. The moral of the story is to not trust it too much - just buy gas before it gets to low.

Tom
[/b]

Ya, that's what happened to mine. It sat at full bar for nearly the first 100 miles, then suddently dropped to 8.
I find that odd.

[Bill Merchant]

<div class='quotetop'>QUOTE(whereisz @ Jul 10 2007, 07:19 PM) [snapback]476550[/snapback]</div>

Ya, that's what happened to mine. It sat at full bar for nearly the first 100 miles, then suddently dropped to 8.
I find that odd.[/b]

Welcome to the mysterious world of Prius...

When it start blinking the final pip, GET GAS IMMEDIATELY!

[Marlin]

<div class='quotetop'>QUOTE(whereisz @ Jul 10 2007, 10:19 PM) [snapback]476550[/snapback]</div>

Ya, that's what happened to mine. It sat at full bar for nearly the first 100 miles, then suddently dropped to 8.
I find that odd.
[/b]

Do you also have another car with an old-fashion needle-based gas gauge? If so, go fill it up and see if the needle sweeps past the "F" at the top of the gauge and then stops on a little peg (also known as "pegged"). Then see how many miles it takes for the needle to come off that peg and sweep down below the "F" on the gauge. It's the same thing on the Prius. It's just that on the Prius, anything past where the "F" would be on a needle gas gauge shows up with all the bars displayed.

Depending on the car, you might also notice, if you were to pay close attention to it, that your needle-based gas gauge is not linear and that it moves faster near the end of the tank than at the beginning. It's the same thing on the Prius.

[ZA_Andy]

It seems odd to me that many people who have no problem understanding the behavior of non-linear fuel gauges on other cars seem to have so much trouble understanding that the one in the Prius is really no different.

In my last car, filling up resulted in a gauge that read above full and only started dropping after 2 or 3 gallons. I find the Prius is pretty much the same, except that 3 gallons means 150 miles! After the first blob disappears, the gauge seems to behave predictably enough, though perhaps many Prius owners don't need to fill up often enough to become as familiar with their gauges as they would in most other vehicles!

[Marlin]

<div class='quotetop'>QUOTE(ZA_Andy @ Jul 11 2007, 08:28 AM) [snapback]476722[/snapback]</div>

It seems odd to me that many people who have no problem understanding the behavior of non-linear fuel gauges on other cars seem to have so much trouble understanding that the one in the Prius is really no different. [/b]

I'm not surprised. I would expect that most people in their other cars never really paid too much attention to their gas gauge. It's something they would glance at every once and a while inorder to answer a simple question: "Do I need to get gas today, or can it wait until another day?"

However, once they buy the Prius, they are very concerned with how good their gas mileage is. So now instead of looking at the gas gauge to answer a simple yes/no question, they are trying to answer more evaluative questions such as "How good am I doing?" or "How much farther can I go on this tank?". Its the first time they've ever tried to get precision answers from a gas gauge, and therefore they are only now discovering that gas gauges are not very precise.

[qbee42]

<div class='quotetop'>QUOTE(ZA_Andy @ Jul 11 2007, 08:28 AM) [snapback]476722[/snapback]</div>

It seems odd to me that many people who have no problem understanding the behavior of non-linear fuel gauges on other cars seem to have so much trouble understanding that the one in the Prius is really no different.

In my last car, filling up resulted in a gauge that read above full and only started dropping after 2 or 3 gallons. I find the Prius is pretty much the same, except that 3 gallons means 150 miles! After the first blob disappears, the gauge seems to behave predictably enough, though perhaps many Prius owners don't need to fill up often enough to become as familiar with their gauges as they would in most other vehicles!
[/b]

I think part of the problem is that the Prius gets exceptional mileage. It makes it hard to guess how far you can go on the gas you have left. For example, say you are driving an SUV that gets 16 mpg under good conditions, but today you are blasting down the highway so your mileage has dropped to 15 mpg. With one gallon of gas left, you assume you can drive 16 miles before running out, but in fact you can only go 15, causing you to over estimate your remaining miles by one.

Now lets look at the same situation in a Prius. You normally get 53 mpg, but today on the highway you are only getting 43 mpg. With one gallon left, instead of 53 miles, you can only drive 43. Note that you can still drive almost three times as far as you could with the SUV, but the SUV's crappy mileage is fairly consistent, since it is throwing away a lot of energy all of the time. This is why the Prius doesn't include a "miles to empty" calculation on the MFD. To be at all meaningful, the computer would need to know where you were planning to drive, how fast, and traffic conditions. Combine that with the built-in inaccuracies of the fuel tank bladder, and you just don't know how many miles you have left in the tank.

Get gas when you get down to one pip. Get gas NOW if it starts flashing.

Tom

[quagmire0]

If it were a pip a gallon, I would have been getting 150mpg the other day. If only...