Inaccurate Mpg Indicator

[jonnyl]

The MPG average indicator consistantly reads about 15 - 20% high compared with the old fashioned way of measuring the miles and fuel used. Highly misleading, probably delibarate. I would expect a bit of an error but 20%, Toyota should have a duty to ensure instruments are reasonably accurate. When I test drove it, I used this information as part of my decision to buy the car.

Also how does it work? I reset it at the garage, drove 300 miles and it read 61.5 mpg. When I filled up again and drove 600 yards it dropped to 20mpg and then started to recover? Weird, my Toyota avensis doesn't do that.

[Red Yaris 54]

The MPG average indicator consistantly reads about 15 - 20% high compared with the old fashioned way of measuring the miles and fuel used. Highly misleading, probably delibarate. I would expect a bit of an error but 20%, Toyota should have a duty to ensure instruments are reasonably accurate. When I test drove it, I used this information as part of my decision to buy the car.

Also how does it work? I reset it at the garage, drove 300 miles and it read 61.5 mpg. When I filled up again and drove 600 yards it dropped to 20mpg and then started to recover? Weird, my Toyota avensis doesn't do that.

On the Mk2 Yaris the MPG Average indicator resets itself each time you refuel. When you pull away after refuelling you have to generate your average consumption again from 0 MPG

I have found my indicator to be extreemly accurate compared to the normal "brim to brim" method of working out fuel consumption.

My calculations indicate an error of less than 2% (quite acceptable to me)

I guess you must add your "innacurate indicator" to the ever growing list of why you really do not want your Yaris..............Maybe you will be more dilligent when you buy your next car ;)

[cabcurtains]

All cars read out slightly, most cars have different read outs parameters as well such as resetting after the engine is switched and restarted or in the case of my Passat after 2hrs, however our Verso has the average MPG based on the last time the entire trip computer was reset which can be a endless i think.

They also do things like looking at the last few miles of driving to work out the range instead of all the miles driven since the last fill up etc etc They should be used as a guide and not taken literally.

[jonnyl]

The MPG average indicator consistantly reads about 15 - 20% high compared with the old fashioned way of measuring the miles and fuel used. Highly misleading, probably delibarate. I would expect a bit of an error but 20%, Toyota should have a duty to ensure instruments are reasonably accurate. When I test drove it, I used this information as part of my decision to buy the car.

Also how does it work? I reset it at the garage, drove 300 miles and it read 61.5 mpg. When I filled up again and drove 600 yards it dropped to 20mpg and then started to recover? Weird, my Toyota avensis doesn't do that.

On the Mk2 Yaris the MPG Average indicator resets itself each time you refuel. When you pull away after refuelling you have to generate your average consumption again from 0 MPG

I have found my indicator to be extreemly accurate compared to the normal "brim to brim" method of working out fuel consumption.

My calculations indicate an error of less than 2% (quite acceptable to me)

I guess you must add your "innacurate indicator" to the ever growing list of why you really do not want your Yaris..............Maybe you will be more dilligent when you buy your next car ;)

Hi,

That makes sense and you can manually reset if you want to.

What method do you use to check fuel consumption indicator other than the brim to brim method? I though this was the most accurate.

Dont get me wrong, I think the car is great just a few small gripes more to do with the sale than the car. It is the 1st time I have bought a new car and it is very different to buying a second hand one. If it is used, you get what you see and it is your fault if you buy it. With a new "off plan" car you have to rely on accurate info from the garage, if it is not accurate you feel mislead.

[HowardL]

Mine says 44.3 mpg

I also done the "logging miles done and fuel used"

It worked out at 44.8mpg

[Red Yaris 54]

The MPG average indicator consistantly reads about 15 - 20% high compared with the old fashioned way of measuring the miles and fuel used. Highly misleading, probably delibarate. I would expect a bit of an error but 20%, Toyota should have a duty to ensure instruments are reasonably accurate. When I test drove it, I used this information as part of my decision to buy the car.

Also how does it work? I reset it at the garage, drove 300 miles and it read 61.5 mpg. When I filled up again and drove 600 yards it dropped to 20mpg and then started to recover? Weird, my Toyota avensis doesn't do that.

On the Mk2 Yaris the MPG Average indicator resets itself each time you refuel. When you pull away after refuelling you have to generate your average consumption again from 0 MPG

I have found my indicator to be extreemly accurate compared to the normal "brim to brim" method of working out fuel consumption.

My calculations indicate an error of less than 2% (quite acceptable to me)

I guess you must add your "innacurate indicator" to the ever growing list of why you really do not want your Yaris..............Maybe you will be more dilligent when you buy your next car ;)

Hi,

That makes sense and you can manually reset if you want to.

What method do you use to check fuel consumption indicator other than the brim to brim method? I though this was the most accurate.

Dont get me wrong, I think the car is great just a few small gripes more to do with the sale than the car. It is the 1st time I have bought a new car and it is very different to buying a second hand one. If it is used, you get what you see and it is your fault if you buy it. With a new "off plan" car you have to rely on accurate info from the garage, if it is not accurate you feel mislead.

I use the "Brim to Brim" method and that gives me the "less than 2%" difference to my in car indicator.

As far as I know the "brim to brim" system is the only accurate method.

[smyffalis]

I use the "Brim to Brim" method and that gives me the "less than 2%" difference to my in car indicator.

As far as I know the "brim to brim" system is the only accurate method.

see this bring to brim method. filling at the local BP, i fill until it clicks 3 times then i leave it. do you take out the pump and squirt in a bit more until you can see the petrol about to overflow? squirt as in very very lightly

[Red Yaris 54]

I use the "Brim to Brim" method and that gives me the "less than 2%" difference to my in car indicator.

As far as I know the "brim to brim" system is the only accurate method.

see this bring to brim method. filling at the local BP, i fill until it clicks 3 times then i leave it. do you take out the pump and squirt in a bit more until you can see the petrol about to overflow? squirt as in very very lightly

It is up to you how you do it...................If you always use the same filling station and same pump you could stop filling "at the click"

If you fill to nearly overflow it might be better in theory, but not necesarily any safer or accurate as you are more likely to spill fuel when filling or driving off.

[jonnyl]

I am using the brim to brim method but my figures are not even close.

indicated - 58.7 mpg actual 47.1 mpg

indicated - 60.6 mpg actual 53.2 mpg

admitedly the actual figures are more realistic but why is the indicator so high, maybe it is only on the new models.

[hertsnminds]

Do you reset all trip computer information or just the Av MPG? Try resetting all trip displays when you fill up.

[cully]

My Y reg Verso goes completely haywire when I fill it to the brim, and then reset the odometer and trip button.

I get seemingly random displays showing anything from 0.0 to 99.9, and they change much faster than usual (which is about once every 0.3 mile). Then, after about 20 miles, everything settles down to a believeable (49.7mpg), slowly changing figure.

I had been thinking of raising this myself, but am somewhat cheered that others may have the same question.

I assume that the excess fuel standing in the filler pipe (I still have the habit of filling right up) gives one of the instruments a fit, so that it cannot provide a proper calculation. My guess is it's the fuel gauge.

[carlowlad]

Hi Cully.

What you are describing there is what happens after you reset the average fuel consumption, or AVE mpg. Because it is calculated over distance, the first few miles will be almost like the instant mpg as your consumption will indeed vary from terrible (up a hill) to unbelieveable (engine braking down a hill or to a red light) It isn't gone haywire, it's just giving you an accurate reading as to how your average mpg is up to that point.

Say for example you didn't reset the average mpg gauge at all. In a years time, you could enter your car in a rally and your average consumption would hardly change at all. This is due to the large distance covered and the amount of fuel used.

I have a scangauge and it does the same, as has every mpg gauge in all the cars i have driven. I also fill to the brim without any ill effects or wastage. Hope i didn't lose anyone there! I've just come off nights!

[waxxy]

since i bought my car 3 weeks ago ive refilled it twice and each time the pumps have made a clicking sound and not let me use them so ive had to try another pump and then itll work..now the pump shouldnt click because the fuel indicators flashing but the hand pumps are clicking like its full ..

the woman at sainsbury said she thinks theres a fault with my car as the pump didnt make clicking sounds before i used it..what do you guys think?

[carlowlad]

I've seen some pumps do that. If you hold the nozzle out a little and open it gradually it should pump ok. It reads the back pressure so if the nozzle is pressed up againt the inside of the filler neck, it may feel enough back pressure to trip out the pump. If it's one of those pumps that won't let you restart the fill then you are in for an annoying walk to the "assistant" to get the thing restarted.

I'm no expert in this field, just personal experience, so feel free to correct me on anything i've just said.

[waxxy]

I've seen some pumps do that. If you hold the nozzle out a little and open it gradually it should pump ok. It reads the back pressure so if the nozzle is pressed up againt the inside of the filler neck, it may feel enough back pressure to trip out the pump. If it's one of those pumps that won't let you restart the fill then you are in for an annoying walk to the "assistant" to get the thing restarted.

I'm no expert in this field, just personal experience, so feel free to correct me on anything i've just said.

hey you could be right mate.ive been driving a astra for years and what i had to do was push the nozzle in all the way to get the petrol in so ive been doing the same ive been pushing it in as hard as i could lol..ill try the gentle approach next time lol

[waxxy]

ive never had any type of trip computer in my cars before so im a little clueless using or reading them im getting 58 mpg as my average mpg on the screen.

i find it confusing the pumps sell in litres but the cars measure in gallons :( all i know is my computer reads if i put 18 litres in i get about 175 miles left on my screen.

.ive just found a convertor on the which website that says theres 4.55 litres in 1 gallon so if i put 18.2 litres in my car in theory i should be able to drive about 232 miles but im not getting anywere near this im lucky to get about 160-170 before the refill light starts flickering.

will we get better mpg the longer we drive the car and break it in?my cars only done 450 miles im gonna have a party when it hits 1000 lol

heres a link to the convertor --

http://www.which.co.uk/advice/litres-to-ga...llons/index.jsp

[carlowlad]

MPG will improve as the engine breaks in.

On your mpg display there should be an option to change it to L/100k. I have a kia ceed and by holding a button down for a few seconds it changes it between metric and imperial. Have a look in your user manual, there might be something there.

The low fuel light flickers with about 5 or 6 litres left in the tank so the distance you'd cover on that might bring you close to the distance it thinks you'll cover. I've gone as far as 2 litres left in the tank......that was a close one!

[waxxy]

in my old astra once it hit the red i still ran it for 3-4 days lol..but im not trying it with the new one .

[smyffalis]

It is up to you how you do it...................If you always use the same filling station and same pump you could stop filling "at the click"

If you fill to nearly overflow it might be better in theory, but not necesarily any safer or accurate as you are more likely to spill fuel when filling or driving off.

cheers, filled up yesterday at the same pump ive been using for a while now. BP Ultimate one. i do 3 clicks then take it out which i have been doing. ive filled up too much before once at a tescos garage, it was a clicky pump no matter what angle i held it at, and i was looking at the price and litres until i turned round and saw that it was spilling out. i was so embarrassed haha

and to waxxy. i get that aswell, but if you reset your trip and count the miles travelled, you will see that it is accurate, but not that accurate. you will get more miles than what the display says if you just drive like a normal person

[waxxy]

thanks smitty ill read the book on how to reset the computer.

[smyffalis]

thanks smitty ill read the book on how to reset the computer.

just press the odometer button until it displays trip a or trip b. then hold it in to reset. or else take note of your current mileage

[cully]

Thanks, Carlowlad - I certainly don't disagree with your maths; the rate of variation will certainly slow considerably as the distance travelled increases, and I certainly see that as a regular thing.

What I'm seeing, though, has no connection with the engine load - accelerating up a hill can sometimes (but not always) give a reading of 70 or 80 mpg, while coasting up to lights with my foot off the accelerator may bring a drop to 0.3 or even 0.0!! After twenty miles or so, there's no way that that can be a correct result; the tank should be empty!

As I say, everything returns to normal after about 20-30 miles without any intervention on my part.

I was just wondering if anyone else had suffered the same, and whether it heralded a failure coming up in the near future.

Thanks Cully

[carlowlad]

Cully, that is weird. Have you done the "turn it off and back on again" trick? You never know, it might just work. You'll lose your radio stations so it depends how much this is bothering you! But i've seen electrical stuff in my job doing very strange things much to the electricians frustration. I always joke about turning it off and back on again and it actually works a lot, much to their frustration! :D