Prius's MPG is not accurate

My first gas-miser car was a 36 horsepower 57 VW Beetle: it didn't even have a gas gauge. At each fill-up I would try to remember to jot down the odo reading on a piece of masking tape stuck to the dash board, and then fill it up before I'd gone past 300 miles or so. If that tactic failed, it also had a reserve tank which was accessed by turning a lever underneath the dashboard (I would lose vision only for a moment while ducking down to locate the lever, but in this car I was never going very fast to pose much of a danger), the car would sputter for a moment, and then I was good for another 50 miles. So, why not use a Prius version of this tactic and fill-er up before you've reached 350 miles on a tank? Works for me in my '08.

Although the '57 Beetle got great gas mileage, it was an air pollution nightmare not to mention its lack of safety features (we don't need no stinkin' seat belts). But a 60's hippie didn't worry as long as long as the peace-symbol was still visible in the oval back window.

 

The Prius Guess Gauge is Inacurate?!? Stop the press!

 

Uh keeping a gas can in the car is extremely dangerous. Your call I'm just saying.

 

mine is under 1MPG

 

Dead horse, anyone?

ALL gas gauges are inaccurate. My last went forever at full, then dropped like a rocket, then went forever on empty. the one before that was more linear, but still hung at full most of the time, and died immediately at empty.

The refill thing seems a large problem on a few (relatively) vehicles, or maybe it is just the operators are less forgiving or observant.
I know when my last blip flashes I can only put 8-9 gal in. I have no idea how much is actually in my tank, but I know how far I can go on that "full" tank from past observations. If I am going to drive 300 miles, I fill up before I leave and I know I will not have a problem. I fill up before I return home. I don't feel the need to drive until the last drop.
Not a problem.

 

the MOST pathetic thing about this thread is what??

the assumption that the meter on the gas pump is accurate (highly unrealistic expectation without a HUGE expense involved)

before we got instant feedback on our mileage, we were assuming our mileage (other than long trips, i rarely tracked my mileage on anything resembling a regular basis and wondering how many of you here have?) resembled the EPA's?

i find it somewhat confusing that we would think that the one of the most advanced and successful engineered product in the automotive field would be "significantly" inaccurate.

am i to think that many of you here think that Toyota purposefully programmed the odometer and MPG info to skew to read higher than actual mileage? doesnt say much for their reputation

or am i think that the engineering team thought it not important enough to get close to the real mileage? or am i to think they did not have the ability to be accurate?

well, i guess all those thoughts are a possibility.

but i prefer to think that the gas pumps i am using are wrong.

Is Your Gas Pump Ripping You Off? - CBS News

ya, read this.... 600 inspectors responsible to making sure that gas pumps are accurate...600 FOR THE ENTIRE UNITED STATES...

now, not questioning their ability to do their job... i am questioning the ability to do their job in a timely manner though...

now have said this a few times. i guess it bears repeating. i was a victim of an inaccurate pump back in 2005 and the accuracy of my Prius was what revealed the issue.

i noticed a station i used that seemed to always read a bit low. so i used the same pump 3 times in a row since the bladder makes it impossible to use 1 or 2 tanks and all three times i read between 1.2 to 2 something mpg lower than the car's reading. well i reported it, 6 months later i received a letter verifying issues with the accuracy of the pump.

during my waiting time, KING-5 News did a show where had independent company measure a few hundred pumps in the Seattle area... about 15% were beyond to accepted tolerance level for accuracy and 4 in 5 favored the gas station. it was determined that the metering system used does wear out over time and starts to read high (iow a gallon displayed is less than a gallon dispensed)

so before you bash your Pri... remember that on average, 1 in 10 gas pumps are RIPPING YOU OFF

 

Having just labored to get through this thread, the BEST idea to pop up is from our Friend down under, "Patsparks". When you see 2 pips, fill her up! Its so simple it hurts to disagree. I personaly follow this technique and find I put in 8.5 gal, and get just under 400 miles. SIMPLE. If you put so effort into driving that gas gauge down to its very bottom end, you just gonna be walking . I would then suggest you buy the cardboard fold up gas can. You are realy making this FAR harder than it really is.

2 pips down, wheres the next Shell station aound!!!

 

On the contrary, it is poor advice by someone who doesn't even have the bladder.

At 2 pips my fills are about 7 gallons (sometimes less, sometimes more.) I get about 8.5 at the flashing pip. This is nowhere close to the tank's rated capacity, so if I end up walking there will be some warranty work to be done. And I would rather have such a problem identified and fixed under warranty rather than out of warranty. Hence, my qualification of Pat's suggestion as very poor advice.

 

It is only a problem if it runs out before the gauge is down to one pip.
I have NEVER been able to put "rated capacity" into a tank, on any of my 6 vehicles, even on the two that had been run to empty.
one was a 17 gal that was able to hold 19, and another was a 15 gal that held 13.5.

 

Shawn, you are entitled to your opinion.
I only once in my life ran out of petrol and two things happened that, apart from my stupid slackness in not filling at 1/4 of a tank as is recommended in almost every car user manual. The warning came on that I needed to get fuel, a flashing petrol pump picture on the dash display and then in under 5 km I was out of fuel. The second thing was that the Holden Commodore I was driving had the V8 fuel gauge calibration not the V6 calibration, that's why I had so little warning. That has been fixed now.
I'm still driving that GM Holden Commodore for work, it is due to be replaced soon.

The gauge in the Commodore is still one that drops slowly for the first half of its travel then falls like a stone for the second half so it can catch you out sometimes. That gauge is also not mounted in the centre of my view but tucked behind the steering wheel, how dumb are GM?

I'm still waiting to read about the person who ran out of gas at 2 bars on the gas gauge, bladder or no bladder.

Let me work this out, with 8.5 gallons and 55mpg I can get 465 miles out of that. My last car, a Camry had a 60 litre tank, the mileage rating for that was about 8L/100km so if I ran the tank dry I could have got 750 km from the full 60 litres or 466 miles.

All this fuss about 1 mile! I don't need a bladder to work this out, and I would always fill my Camry at 600km anyway.

 

I strongly disagree. The advice is practical and cautious. There is no harm in that for the driver who doesn't mind refilling slightly more often than necessary. A wider margin of error than for most cars is sensible, given the particularly serious potential consequences of running out of fuel in the Prius -- irrespective of the bladder.

 

ItzaGasCan Collapsible One-Time Use Gas Can

 

Hey, patsparks,

Regarding your following quote about running out of gas with 2 bars :

See this thread, specifically post #1 and also post #12. I had a little bit of a hard time finding it again, but I did remember reading it a while back. Maybe you just didn't remember it from back then either (over 13 months ago) because you responded to the OP in your post #5.

http://priuschat.com/forums/prius-main-forum/45425-gas-gauge-didnt-show-empty.html#post595528

Ken (in Bolton,Ct)

 

That's scary.

... Brad

 

It has been quoted for you by another poster, not one, but two examples. Plus I'm pretty sure that I originally read of this happening in a different thread.

So now we can safely put your whole theory to bed. The problem with it is your approach is a band aid that will only hide the problem from the owner...and perhaps until out of warranty. As such it is not smart advice, it is advocating blissful ignorance.

I even more strongly disagree with the above. It is neither practical nor cautious. What is cautious about hiding a problem from the owner so that it can surprise him/her later when he/she will have to pay for it? That's not cautious, it is foolhardy! This creates the ILLUSION of being cautious while making it harder to detect actual problems. And make no mistake about it: having the vehicle go empty before the flashing pip is a problem with the gauge/tank--and one that should be remedied by the manufacturer.

Plus I disagree with the consequences of running out of fuel in a Prius. Unless the driver is retarded the consequences are less serious. First of all, the battery pack provides additional range to get the car to a safer position or gas station if necessary. That's a benefit over the standard gasoline powered vehicle which is stuck once the engine shuts down. And there is no reason that a person should have to run the battery dangerously low. In fact where I've heard of that is instances where the vehicle shut down and was restarted several times. (See "retarded.")

What such "caution" is likely to do is mask a problem long enough that the owner gets a nasty surprise in just the sort of situation in which they cannot to run out of gas in.

I'm not saying that people should drive on fearlessly the first time they go down to the flashing pip. Instead do it at a time in which you can easily deal with running out if it occurs. Once you have a fill or two in that range out of the way, the concern goes away.

It makes more sense to test and calibrate your system, than to run blindly as you advocate. A well informed driver that knows his/her vehicle has an advantage.

It is silly the extremes some will go to to baby this tank. At a flashing pip the most I've managed to put in is 9.3 gallons...leaving a 22% theoretical buffer. Most often I get in 8.5 gallons, nearly a 29% buffer, 3.4 gallons. I've run my three other Japanese vehicles down to within half a gallon of rated capacity and never run out of gas in any of them. If this tank runs out at 8.5 gallons from a fill and before a flashing pip, then I want to know--and it will be headed to the dealer in short order!

 

[deleted]

 

I know this is a bit late for this thread but has anyone considered resetting the AZ and EL sensors? They are used to 'correct' the fuel gauge. If the fuel gauge is ever off, Toyota recommends resetting them. THe reseet process is quite easy. If anyone is interested, IM me and I'll post it here (gotta go dig to find it).

 

Actually the spare can goes in the car when I'm planning to purge the gas in the tank. I usually put it in the trunk of my NHW11 when the fuel level gets to the last couple of pips. With over 30 fuel starvation events, I'm finding the blinking pip means:

• 25 miles - minimum to engine stop
• 65-75 miles - typical
• 130 miles - longest

Now that we've finally gone to 10% ethanol, it is time to repeat my fuel tests.

Bob Wilson

 

This has been dealt with before somewhere here. Most people trust the mpg readout over fillup calculations. They almost never agree. The bladder error probably depends on ambient temperature. Since the fillup gallons can vary, it's tough to gauge the accuracy of the fuel meter. Sometimes, it takes mine a mile or two for the gauge to show full after a fillup.
I had a BMW Z3 with a fuel gauge that was off by a quarter tank--due to a notorious fuel sender problem those cars had for years BMW never acknowledged.

 

You know you seem to be the only one out here complaining that at a flashing PIP you can only max out at putting 8.5 Gal of fuel into the tank. When I put 8,5 in at 2 pips I can be reasonable confident that I have at least 2.5 gal left in my tank. I would drive it dry to prove my point, but that would just be plain stupid. Besides I have not bought my little cardboard gas can yet, something I would think would be a mandatory accessory in your car.
You need to stop banging on folk so hard just because they choose to err on the side of caution, and the risk of looking stupid when you have to admit you "Ran out of gas" DUH!!! Dumbshit move #1 in the Auto world!!! I have NEVER ran out of gas since I started driving in 1967!!!

I submit that if you can only get 8,5 in your car with only 1 flashing pip, your car needs to visit Mr. Dealer and let them recalibrate your fuel system, or get the bladder replaced. To think that we all are going to plan our fillups based on your reckess abandon just because you drive a car with a defective guess guage is NUTZ...

Dude snap out of it!!!

Just one mans opionion!!!