Fuel economy readout is false!

[stripey]

Anybody else find that on their Yaris the fuel econony, although good, is nothing like as good as the the in-car visual display claims it is?
I regularly get 44 - 46 miles per gallon out of my Yaris Verso, but when I do, the little screen claims that we're getting 60 - 64. I reset it every time I fill up and always fill the tank right up, so what's going on here?

Is it boosted high just to sell the cars in the first place, I wonder?

[roxy1]

Originally Posted by stripey

Anybody else find that on their Yaris the fuel econony, although good, is nothing like as good as the the in-car visual display claims it is?
I regularly get 44 - 46 miles per gallon out of my Yaris Verso, but when I do, the little screen claims that we're getting 60 - 64. I reset it every time I fill up and always fill the tank right up, so what's going on here?

Is it boosted high just to sell the cars in the first place, I wonder?

i'd say it is safe to say most of us here dont have that problem

...............since we dont get the mileage display

[BailOut]

Hi Stripey,

As was mentioned the NA Yaris does not get the MPG display. Only the hybrids get it.

The hybrid's display tends to consistently read 5-10% high but what you are reporting is way off of that. Could it be the difference between Imperial gallons and US gallons at play? If not you should visit a dealership to have it calibrated or replaced.

[stripey]

All the Yarises in the UK have it, and the difference is more than that between US and Imperial gallons. I'll mention it at the next service, but as I've learnt simply to read 75% of what it says, I'll let it be unless they'll do it free!

And although I bought this car in Denmark, it is supposedly UK spec, although the chaps in Japan may have got confused over units!

[marcus]

i say post a formula for calculation. other member uses different formula on this.. i still dont get people getting over 840km on a 36liters of gas??? even me driving 90km/hr all the way i dont think ill hit that..

[YarisSedan]

So you actually have a display that shows your MPG on your dash? Why dont we have those! Atleast you have one!

[m911gt]

If he is talking about the displayed estimated MPG, the problem could be the measuring apparatus of the tank. If the measuring mechanism is fairly cheap, it consists of a vertical bar that takes measurements in the vertical direction and converts the vertical displacement of fluid into a digital signal and displays the value on the dash. The problem with this type of measuring system is that the measurement is taking into account vertical displacement only, when it should be measuring a volumetric change, hence the estimated amount of fuel left in the tank is an incorrectly high value. The correct type of measuring system (measures volumetric change) is a four-bar mechanism which has a pivot that allows a more accurate measurement to be taken.

If this isn't what you're talking about, I apologize...that's all I know about the potential issue. Also, if anyone needs to make a correction to my explanation, please do.

[stripey]

Originally Posted by marcus

i say post a formula for calculation. other member uses different formula on this.. i still dont get people getting over 840km on a 36liters of gas??? even me driving 90km/hr all the way i dont think ill hit that..

Mine are imperial gallons, so 45 mpg comes out as 15.86 km per litre

(Divide by 4.54 then multiply by 1.6)

which comes to 571 km for 36 litres.

[stripey]

[QUOTE=m911gt;278488]If he is talking about the displayed estimated MPG, the problem could be the measuring apparatus of the tank. If the measuring mechanism is fairly cheap, it consists of a vertical bar that takes measurements in the vertical direction and converts the vertical displacement of fluid into a digital signal and displays the value on the dash. The problem with this type of measuring system is that the measurement is taking into account vertical displacement only, when it should be measuring a volumetric change, hence the estimated amount of fuel left in the tank is an incorrectly high value. The correct type of measuring system (measures volumetric change) is a four-bar mechanism which has a pivot that allows a more accurate measurement to be taken.
]

Could well be this, but then I would expect some other Yaris owners o recognize the problem. I suspect you're right, as my fuel gauge is very susceptible to the car being left on a slope.

[marcus]

Originally Posted by stripey

Mine are imperial gallons, so 45 mpg comes out as 15.86 km per litre

(Divide by 4.54 then multiply by 1.6)

which comes to 571 km for 36 litres.

now if this calculation is right then im getting 45mpg im doing about close to thesame 570-585 on a 36 liters..{7 bars}

but based on other calculation im doing about 38mpg.

[stripey]

38 miles per US gallon?
That's about the same as 45 per Imperial (English) gallon