Prius gas gauge

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

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!

 

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

 

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

Welcome to the mysterious world of Prius...

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

 

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

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.

 

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!

 

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

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.

 

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

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

 

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

 

I think there may be more serious problems with Prius gas gauges than just non-proportionality and MPG sensitiveness. I just spent 2 weeks with a Prius from National Car Rental in Louisiana, and put on 1,700 miles. I purchased the "fuel service option" (permission to bring it back almost empty) so I paid close attention to gas, and I observed some very strange behavior, unlike any car I've owned myself.

Despite the lack of a yellow gas warning light (just the blinking blue square), the blinking warning in my case was only good for 10 miles or so, before the large exclamation triangle + check engine light + beeper sounding continuously. Luckily I was right at a station at that moment, but this is pretty poor warning for a car in the hands of a stranger (me the renter). My own cars all have given 50-75 miles after the yellow light comes on.

Towards the end of my rental, wanting to keep the tank near empty (2 blue squares) I added a little more than 2 gallons which I assumed would light up a total of 4 squares. But no, the gauge stayed at 2 squares and continued to show 2 squares while driving almost 150 more miles.

Then I added 1 more gallon, and instead of going up, the gauge went down, to just 1 square!

I drove very slowly (60 mpg) back to Louis Armstrong Field to return the car, not having much faith in my gas level at all. I made it OK but I wouldn't be happy about this at all if I owned one.

 

I've run out of gas twice (surprising, right?). The first time, the last square started flashing and the display said "Add Fuel" over eighty miles before I needed to do so; for this reason, I trusted the condition would have lasted longer than the nine miles it did before the second time I ran out. Granted, the second time was on the highway where I was more consistently using the motor and under more load, but that's a hell of a big difference.

I guess the moral of the story is not to run out of gas in the first place? I'm trying to stay red-triangle-and-"Problem"-free.

Slightly OT: You'd think Toyota would put something less generic than "Problem" on the display when you run out of gas! I suppose it's clear enough that the fuel gauge is completely unlit, but a more specific warning might be appreciated.

A bit more OT: How did you like New Orleans?

 

I just bought my used 2008 Prius a couple months ago. I've filled it twice, averaging 45mpg. My gas gauge just went to 2 bars. How far can it go before light comes on? Thanks for your help.

 

2 bars doesn't really mean anything except you are about a 1/4 full. Blinking last light - Don't depend on mpg, the wind or saving .02 cents. As many have reported already, when you search, when it blinks its telling you get gas NOW.

I personally think the gas guage was designed by the oil companies. Why would you put a non linear device in something that supposedly should have linear fuel going through it. Full tank you drive sloppy and don't worry about stepping on the gas to get there. On empty you drive like grandma going to church with the police on your tail following waiting for you to make a mistake.

 

I had driven over 30 miles blinking without running out of gas when I ran out after blinking in 7 miles.

Lesson learned:

Mother in Law in car, get gas at 3 bars (how often do you want to be stranded with her?)
Wife in car, get gas at 2 bars (How soon will she let you forget)
Solo, get gas at 1 bar. (it is a long walk to gas)

In practice I get gas at 400 miles.

 

I never try to run any of my cars out of gas before refilling. Why do that? it cost the same to keep the car full or to keep it empty. At 2 bars I refill and spend around $20.

 

Pay day is friday and it's thursday.

 

Has anyone ever owned a car that the gas gauge was "dead-on" accurate? I certainly have not .... but I never expected the gauge to be perfectly accurate. Guess what ... the speedometer has an error also, as does the odeometer. I hate to break the news .... the outside temperature gauge is not absolutely accurate either. But neither are the filling station pumps completely accurate .... that is why the state has inspectors whose job is to sample and calibrate the delivery systems.

Within each pip, there are a lot of miles. When my gaiuge first goes to the center, I think, Oh, I am not doing too good this tank. Then it remains there for well past 250 miles. Also, if you have not noticed, even with only 1 pip showing, there is still 2-3 gallons in the tank. No, each pip does not represent 1 gallon .... else there would be 11.9 pips (or however many gallons the tank holds)

Some responders seem intent oin finding fault with every issue. I suppose it is a law of physics ... for every action there is an equal and opporite reaction.

Is the problem a lack of confidence in Toyota? the Prius? or Hybrid technology? How many threads read: ... What is that sound? Is this normal? Does your do this? I consider myself so lucky .... Toyota got it all right on my G3 .... I have no issues with unidentified sounds; no rattles, great ride; great fit and finish; fine radio reception; once I read the manual the NAV works great; and fantastic fuel efficiency. This month I leave on a 6000 mile road trip and I am really looking forward to the ride.


Anyone interested, read the most recent issue of Consumer Report ... they have several interesting observations re EV's. I thought among the most interesting is the statement regarding how much environmental components (A/C, heater, radio, lights and etc,.) will drain the battery ... thus range.

 

My father has a 2004 prius and loves pressing his luck. When his tank goes down to 1 pip, he tells me that translates to "one or two more days" til he has to get filled up.

In my 2006 prius I purchased this week (like father like son!) I dont see myself ever bothering to press my luck (NOT like father like son!), plus, after you hit 400+ miles on one tank, why bother trying to go to the last drop, hasn't your car earned a fillup?

Also, I have never had a car with an accurate gas gauge. They all take forever to hit halfway then drop rapidly after the 50% mark. Just the way to ball bounces. We just are more sensitive to it in a Prius since everything is tracked, monitored, digital, analyzed and scrutinzed more than any other car.

 

I actually called the dealer and told them I thought that the gas gauge was off. (I did buy used and the 1 month, 1000mi warranty is almost up). They said it has a bladder which gives you an approximation. My prius has an 11.9 gal gas tank so if I'm getting around 50 mpg I should get 595 mi per tank. I've also heard it isn't good for your car to let the gas tank get too low since deposits can get sucked up into the engine. I figure I will fill around 450mi.