Accuracy of Fuel Consumption

[Hamstor]

How do the rest of you find the accuracy of the fuel consumption reading?

I just got my Aurion, on its first tank, fill to fill the dash reported reported 10.0, however I pushed in 56.51 litres and the trip metre read 523km. Thats an actual economy of 10.8, nearly a full litre per 100km more than the dash reported.

[Mr De Angelo]

Actually my fuel consumption often shows more than it uses. Mine correlates to the Distance remaining, meaning my tank usually still has a bit of juice left and does under what is stated.

[RickyZR6]

hi people......

I have found my dash to sometimes be all over the place.........sometimes the fuel light comes on and the dash says 70 Km till empty?????

I found it strange so i asked Toyota to check it for me which they said the diagnostics computer said it was fine ( im sure? ) and the computer test ok. Normally the light only comes on when i have 40 to 50 range left. which is pretty spot on.

[DJKOR]

The average fuel consumption meter on the dash is reasonably accurate, but is only really useful to get a rough average. To really know your fuel consumption, you need to pay attention to your actual fuel used over a measured distance.

Before we go into details through another thread, we should try to keep things together in threads that already exist.

Some discussion about average fuel consumption as per the reading on the dash was established in the following thread:

Fuel economy advice

Then if you really want to see what fuel consumption you are really getting, you can submit your manual calculations here:

Aurion average fuel consumption

You need to note though that the cruising range does not always count km for km. If you give your car a bit of a push while driving, those km's will count down quicker than if you were driving more sedately.

[EC11WA]

I find the fuel consumption to be quite accurate.

The new 09 TRD is getting just on 10 litres per 100km...this is pretty much 75% highway and 25% city driving. Quite impressed and that includes a heavy foot at lights........

Can someone confirm that the fuel tank is 70 litres. The only issue ( not really an issue ) i see is that the cruising distance shows 100km left when i fill up yet the tank can still take another 15 litres to full.........so in reality i should still be able to get another 50kms when the cruising distance shows zero. I take it the exra 5 litres is for the spout leading to the tank......

[corhijas]

just my 2 cents worth,

i would'nt fully the electronic gauges as they have built in margins for error etc,my fuel light also comes on with at least 10 or more litres in the tank.

the way i judge my fuel economy is to fill the tank the same way as much as i can and use the km,s per litre theory.

i fill the tank till it clicks full and then add to the nearest dollar,work out the economy this way a few times and you will get a reasonably accurate reading.

in regards to fuel economy the average i get which is mainly highway driving and probably 10% hard throttle driving is around the 9litres per 100 mark which i find reasonable at the moment.

everyones habits are different so each engine/gearbox will be different

cheers corey

[corhijas]

the book says 70 litres so i would asume it is,also my light comes on just above the empty mark and if i fill it up asap the most i have been able to get in is about 56 litres and that includes filling right to the neck like you would with a diesel

cheers again

[EC11WA]

Its nice to know that when your light comes on and you fill up, that it only takes 56 to 58 litres. I am the same and just above Empty. This leaves a nice buffer for error in case one forgets to fill the tank. Still have a goo 12-14 litres in the tank.....unless of course Toyota were wrong and its only a 60 litre, then i would be up s**t creek as not all servos in Perth have PULP98.

Also knowing you are not running the tank right down to zero and getting all the crap from the bottom of the fuel tank aswell.

I actually work in the fuel industry ( not at a servo ), and the amount of crap in fuel nowadays is unheard of.

[David the Viking]

The tank IS 70 litres in capacity. The fuel light comes on when there is approximately 15 litres left which is also when the distance to empty will display 50km to empty.

I have found that the fuel consumption accuracy can be out by 0.5 l/100km.

Edited September 29, 2009 by SupaTouring

[DJKOR]

Can someone confirm that the fuel tank is 70 litres. The only issue ( not really an issue ) i see is that the cruising distance shows 100km left when i fill up yet the tank can still take another 15 litres to full.........so in reality i should still be able to get another 50kms when the cruising distance shows zero. I take it the exra 5 litres is for the spout leading to the tank......

As said, it is 70 litres. Just for reference:

Fuel Warning Light

I actually asked a similar question to this before:

Fuel tank and gauge accuracy

And the Corolla guys asked as well:

Corolla Fuel guage?

After many, many more tanks of fuel and others claims to back it up as well, we have found that once the gauge needle is on empty and the 'Cruising Range' says '0km', you have about 10 litres left in the tank and can travel roughly another 70-80km. I find my fuel light comes on when my cruising range drops to about 30km or so and/or when the gauge needle reaches about 1/8.

General camry questions/answers

It seems to be a common thing for Toyota fuel gauges to show empty when there is 10-15 litres left in the tank. Just for reference, here is some discussion on other models:

Aurion:

Fuel tank and gauge accuracy

And the Corolla guys asked as well:

Corolla Fuel guage?

When you think about it though, it actually makes sense. Think about the surface area of the fuel tank. It's like trying to measure 10 litres of water in the bathtub. The level (depth) of the water isn't that much when you put it that way which makes it hard to measure.

[EC11WA]

Good info guys........gives you peace of mind knowing that i still have some 10 litres left when cruising range shows 0.

[corhijas]

Also knowing you are not running the tank right down to zero and getting all the crap from the bottom of the fuel tank aswell.

I actually work in the fuel industry ( not at a servo ), and the amount of crap in fuel nowadays is unheard of.

its reccomended not to go below 1/4 tank because the pump will suck the s..t into the fuel filter blocking up etc,i try to always fill around the 1/4 mark just in case.

regarding the crap in fuel these days does,nt suprise me at all,i would suggest to stay away from woolworths/safeways outlets as i have been caught out with dodgy fuel on more than 1 occasion and that was with diesel in my old ute,always if possible use a highly frequented station as the turnover keeps the fuel fresh etc.

most dealers will usually tell you to stay away from certain stations as well if you ask.

cheers

[Hiro]

Also knowing you are not running the tank right down to zero and getting all the crap from the bottom of the fuel tank aswell.

its reccomended not to go below 1/4 tank because the pump will suck the s..t into the fuel filter blocking up etc,i try to always fill around the 1/4 mark just in case.

Load of crap. The fuel pump ALWAYS sucks from the bottom of the tank (as that is where it sits), so if there is sediment there it _will_ suck it up, even with a full tank. This is why you have fuel filters, to stop that crap getting into the engine.

Generally you're recommended to not run below a certain amount because of the possibility of starving the fuel pump (even with baffled tanks, this can happen), as well as the high-pressure EFI in-tank pump relies on the fuel to lubricate it (so if it runs dry too much the pump gets rooted). If the pump starves long enough you'll get a significant reduction in fuel-rail pressure, and that can make you run lean, which is not good for the engine (nor the catalytic converter either)

Edited September 30, 2009 by Hiro Protagonist

[EC11WA]

The fuel pumps do not suck from the bottom of the tanks. They are positioned to sit at a certain height above the water level. Yes there is water in all underground storage tanks. Usually a storage tank has 2% water at the bottom. This is why sites turn off their pumps when the level hits a certain percent so that water and sediments do not get fed into vehicles. I have been involved in enough pump outs to have experienced this first hand. I do work in the fuel industry and have done so for the past 10 years.

This is why you fill up at busy sites who are always having a high turnover of fuel. A lot of sites including United here in Perth have been known to run there tanks dry....this can only lead to damage to vehciles.

Also for your information.

Fuel tankers do not have dedicated compartments. A load of ULP or Vortex98 can be loaded into a compartment after the previous load has had Diesel in it. Unless a driver drains off properly, a small amount of diesel will be present in the compartment of Vortex98. This is ok though as i have said, Diesel will sink to the bottom of the Vortex98 tank with the water....this is why the servos allow a small tolerance at the bottom of their tanks and should not run them dry.

For example....as per your statement, thats what fuel filters are for....to collect the crap in your tank.......ok, what if your fuel filter is clogged in your car in a high horsepower engine and all of a sudden you have fuel starvation to the engine.....not a good scenario. Do not run your fuel tanks in your car below 1/4 level. This is the smartest thing i have heard, as its protection against anything that might be sucked up from the servos who let their tanks run low.

My 2 cents.

[EC11WA]

Also note that if you have a contamination, you are unlucky. It is not the sites fault, its the drivers delivering the fuel. The mistake lies with them. All servos including bp are at risk...........

Back on topic.......

I have found no difference in fuel economy in previous cars by using 98 over 95............

I must use 98 in the TRD as i beleive when the TRD was first released, their was an engine failure, speculation led to someone filling the car up with 95 which led to engine failure. This is only because the car is tuned for 98 octane.

So i see no use for people to change their normal cars from 95 to 98 for fuel economy. I do however suggest using 95 as time will tell, the engine runs cleaner, smoother and fuel economy will be only marginally better.

[Hiro]

The fuel pumps do not suck from the bottom of the tanks. They are positioned to sit at a certain height above the water level. Yes there is water in all underground storage tanks. Usually a storage tank has 2% water at the bottom. This is why sites turn off their pumps when the level hits a certain percent so that water and sediments do not get fed into vehicles. I have been involved in enough pump outs to have experienced this first hand. I do work in the fuel industry and have done so for the past 10 years.

I was referring to car fuel pumps, and running car fuel tanks dry, not servo ones. Car fuel tanks don't have a "water level" because unlike underground tanks, car fuel tanks are subject to significant mixing almost all the time they are running. Sure, stuff will settle to the bottom when the car sits stationary for a while, but the instant you go around a corner you have plenty of sloshing, completely destroying whatever layers had formed.

As such, the fuel pickup sits at or near the bottom of the tank (often in a separate baffled or recessed area to help overcome surge problems, but they can still occur)

For example....as per your statement, thats what fuel filters are for....to collect the crap in your tank.......ok, what if your fuel filter is clogged in your car in a high horsepower engine and all of a sudden you have fuel starvation to the engine.....not a good scenario. Do not run your fuel tanks in your car below 1/4 level. This is the smartest thing i have heard, as its protection against anything that might be sucked up from the servos who let their tanks run low.

My 2 cents.

And that is also why fuel filters are removable, serviceable, and replaceable. You are supposed to check them regularly and replace/clean them when they get clogged. And the damage that occurs from a clogged fuel filter is significantly less than that which may occur if those filtered particles made it to the injectors and the engine. If you drive for more than a short distance with a clogged fuel filter you're an idiot anyway.

Edited September 30, 2009 by Hiro Protagonist

[EC11WA]

My apologies, i thought you were referring to Service station storage tanks.

Totally agree when it comes to in Car fuel tanks, although there is still that chance you may have some contaminations in the bottom especially in older cars. It is possible to flush the fuel tank if necessary.

I cannot express the importance of cleaning or changing fuel filters as you have said.

It can lead to poor fuel consumption, car stuttering and if too bad, engine failure........

[Hamstor]

Do not run your fuel tanks in your car below 1/4 level.

You know this is exactly what it says in the manual, but lets face it who wants to fill up on anything but your cheapest fuel day if you can...

[Hamstor]

...

I have found no difference in fuel economy in previous cars by using 98 over 95............

I must use 98 in the TRD as i beleive when the TRD was first released, their was an engine failure, speculation led to someone filling the car up with 95 which led to engine failure. This is only because the car is tuned for 98 octane.

So i see no use for people to change their normal cars from 95 to 98 for fuel economy. I do however suggest using 95 as time will tell, the engine runs cleaner, smoother and fuel economy will be only marginally better.

Back about 5-8 years ago I had a 93 Camry 2.2l, I tried a few tanks of the then named Optimax (now V Power). It made no difference. No noticable power difference and no economy change.

Then I moved to a Eunos 800M, Supercharged 2.4 (miller cycle) which required at least 'premium'. The was little economy difference, but there was definetly a power diff between ULP, Premium ULP and Optimax/VPower.

I now have the Aurion, and plan to use Shell E10, its cheaper and offers more performance the standard ULP. Shell state on their web site their E10 has a minimum RON of 94. A drop from 98, but who is going to notice the difference between 94 and 95?

[EC11WA]

Over here in Perth we have a limited selection of ULP, 95 or 98...all the same just named differently. Speaking to certain people in the industry, there are no plans to bring any Ethanol based fuel to Perth ( for now ). I have heard some good and some bad about it......yes higher octane, but also worse fuel economy.........can someone shed some light on this. I see the V8 supercars have moved to ethanol based and they are finding the same issue, poorer fuel economy. If this is the case, why buy a cheaper product when you don't see any benefit....it is no cheaper in the long run because you are not getting the mileage you once did. I am not certain to how true this is, but yes its what i have heard along the grapvine.....and if someone has any evidence to the contary, please let me know as i have had no first hand experience with this product.

[tekkyy]

The tank IS 70 litres in capacity. The fuel light comes on when there is approximately 15 litres left which is also when the distance to empty will display 50km to empty.

I have found that the fuel consumption accuracy can be out by 0.5 l/100km.

my trip computer is usually optimistic

by about 0.65 L/100km (long term average)

[prometheus]

Do not run your fuel tanks in your car below 1/4 level.

You know this is exactly what it says in the manual, but lets face it who wants to fill up on anything but your cheapest fuel day if you can...

I know someone who is tight with his money , he has a Ford Falcon that he converted to LPG (to save money of course) , the car starts on Petrol and then automatically switches over to LPG.

In order to "save money" he will only put $5 of petrol into the car at a time. The fuel light is nearly always on.

How this makes any econmic sense is beyond me. Having to stop for fuel more than once a week would be a pain in the backside in itself. Each to their own I guess.

[Hamstor]

I think the lower economy is a 'may' not a 'will'. It would be nice to hear from Toyota the pros & cons of using E10 so us owners can make an informated desicion.

So far I havn't seen any noticable change in economy. My second tank (my first on E10, the first tank was standard ULP) was much much more stop start cycle than the more highway cycle of the first tank but I still only used an extra 1 l/100km extra.

I did notice on the bowser at Shell last night it said that E10 economy 'may' be lower. On Shell's web site, their FQ on E10 has a question "Will I get the same fuel efficiency from an ethanol blended fuel compared to regular unleaded?", unfortunately Shell do not actually answer their own question in the FAQ but rather dance around the edges like a bunch of politicians... Makes you think the real answer is yes in many cases. Having said that, E10 is about 4c/l cheaper than ULP, which is about 4-6c/l cheaper than ULP95 which is about 4-5c/l cheaper than 98's like Vortex.

[corhijas]

Also knowing you are not running the tank right down to zero and getting all the crap from the bottom of the fuel tank aswell.

its reccomended not to go below 1/4 tank because the pump will suck the s..t into the fuel filter blocking up etc,i try to always fill around the 1/4 mark just in case.

Load of crap. The fuel pump ALWAYS sucks from the bottom of the tank (as that is where it sits), so if there is sediment there it _will_ suck it up, even with a full tank. This is why you have fuel filters, to stop that crap getting into the engine.

Generally you're recommended to not run below a certain amount because of the possibility of starving the fuel pump (even with baffled tanks, this can happen), as well as the high-pressure EFI in-tank pump relies on the fuel to lubricate it (so if it runs dry too much the pump gets rooted). If the pump starves long enough you'll get a significant reduction in fuel-rail pressure, and that can make you run lean, which is not good for the engine (nor the catalytic converter either)

the etc was what i meant with additional damage being done.

only stating whats in the book plus what mechanics have told me.

[EC11WA]

Personally i try not to go under 1/4 tank for my own peice of mind.

Saying that though, if it is drawn from the bottom of the fuel tank, that throws my thinking out the door.

On another note.

I am getting some incredible mileage from my TRD. I generally run about 100km's a day, i would say at the moment 50% at 90km/h and 50% city driving........looking at the figures, its showing 9.6l/100km. Has only got 3000 km's on the clock and is running like a dream ( touch wood )............Might have to do a trip down south and see what i can get out of a tank.......