Fuel economy advice

[VF-X]

Omg...How did u guys manage to get 10L/100km average? Below 8??!!

I know It's kinda hard to get 10L with 20" and heavier rims...But man, I got around 15L/100km.

Is there something wrong with the way I drive..? Or am i the only one that use Aurion as an in-City Car...?

My uni and home is only like 7 Km apart..

[fuel miser]

I travel 45 k's to work and 45 k's home. Country road 100 k speed limit lots of hills, corners, trucks etc with only 1 80 k speed limit section about 1.5 k's long.

Do the run-around with the kids in the arvo etc.

Try to maintain a constant speed (whatever the limit), read the road/traffic conditions. Mind you I dont spare the horses when overtaking trucks.

I don't drive like an old grandpa either.

[tekkyy]

Is there something wrong with the way I drive..? Or am i the only one that use Aurion as an in-City Car...?

My uni and home is only like 7 Km apart..

don't worry VF-X

15L/100km is normal for city driving

we do suburban driving and we get 13L/100km

no traffic but short roads so lots of braking and not enough cruising

Try to maintain a constant speed (whatever the limit), read the road/traffic conditions. Mind you I dont spare the horses when overtaking trucks.

I don't drive like an old grandpa either.

we tend to place much emphasis on "heavy footed" or not

I believe, barring extreme acceleration, heavy footing its only bad if it causes more braking

I was reading strange graphs (but not of Aurion's 2GR-FE, couldn't find any) about "braked specific fuel consumption"

not sure how it related to read world fuel consumption but it seems small throttle opening is not fuel efficient ?!?!

[Blinkybill]

Here are a couple more for the collection. I actually managed a 4.5 l/100 and a 4.1 l/100, these were both traveling from the caltex servo at mt vic to the start of the m4 (about 50+ k's).

You guys who think that you are actually getting 4.5L/100km or 5.7L/100km by relying on the car trip computer in the first 50km of a tank after a refill I think are a bit naive.

We can see from Tekkyy's results how the trip computer readings are overly optimistic at the best of times and to trust a reading when the fuel guage has barely moved off full is just wrong.

If you really want to find out the truth, then do a refill from a servo after 50km, but please don't trust the trip computer.

[Speedz]

Well i do 124km everyday to GC for work and back so 90% of my trip is on a freeway sitting on 120km/hr on the speedo...

the best i've got is 8.3L/100km... :) with that speed...

probably will come down even more to 7.9L/100km if i stick to just 100km/hr on the speedo...

Edited October 2, 2008 by Speedz

[fuel miser]

Do you believe the cars fuel usage to be wrong? Even with a 10% error at 5.7l/100 it would still only add 0.57 to the displayed usage (still a very impressive number 6.3l/100). This error would be extreme. If you believe it is wrong at the beginning of each tank why would it be any more accurate at the end of the tank? Everyday when I travel home from work the usage will drop 1 - 1.2 l/100 mainly because there is a lot of downhill (goes back up again next day due to hills), this regardless of whether the tank has just been filled or the warning light is on. Do we all fill the tank to the same level every-time? What is the legally allowable error from the petrol bowser? What is the expansion rate of fuel in the tank, does filling it on a cold winter night versus mid afternoon 40 degree summer day make any difference? Are the tires correctly inflated/worn? How accurate is the trip meter or speedo on your car? Obviously the car uses this info to do its calculation, why would toyota go to all the trouble of giving us all these numbers if they didn't believe they were usable for real world driving. When I fill the car and get a cruising range displayed what error should I expect? This number almost always coincides with the low fuel light coming on and at this stage I still have 12 -15 liters left in the tank. Maybe there are too many variables, I think I will believe the car because a calculation involving all these is not for the average guy to contemplate.

Edited October 3, 2008 by fuel miser

[mpresara]

I know there have been a few other threads about fuel economy in the Aurion.

My situation is that the car (an ATX) now has about 4000 km and is 6 months old. It is driven by my other half to work in normal city traffic 20 mins each way and also for shopping trips on the weekend. By no means bumper to bumper traffic. The car is driven fairly sedately, and we aren't racing from the lights. Rarely gets above 3000rpm.

Bear in mind that the advertised fuel economy is 9.9L per 100km.

The last tank calculation has been 44.5 litres for 270 km which equates to 16.5 L/100km.

Now when the car was new, I accepted that maybe it was related to the car being in its first 1000km but this has been the way it has been since the beginning. Fuel economy of 15L/100km or slightly worse.

Best we have had is about 12.5 L/100km on a weekend trip that had a bit of freeway and twisty moutain driving.

Now I rang up our toyota dealer to discuss this and whether a bit of a look to see if the engine was in tune was warranted, and they said well, 16L /100km is not far off what they'd expect ( I'd love them to say this to a new car buyer) for a car before its first 12 month/15000 km service. He said then there will be an oil change and we should get better.

However from reading the other threads with people getting sub 10 readings (granted often on the highway), I'm starting to wonder if everything is OK with our car?

Does anyone out there own an Aurion for which they are driving mainly in the city without much freeway driving with whom we can compare. What do people think? Is this within the norm and we should just put up with it until 12 months service???

Another Presara here, on a trip from say Sydney to Canberra and back I can average 8l/100km. Around Sydney with 50% slow motorway I get about 11litres/100k or better. You really do sound like you have a serious problem?

[mpresara]

I know there have been a few other threads about fuel economy in the Aurion.

My situation is that the car (an ATX) now has about 4000 km and is 6 months old. It is driven by my other half to work in normal city traffic 20 mins each way and also for shopping trips on the weekend. By no means bumper to bumper traffic. The car is driven fairly sedately, and we aren't racing from the lights. Rarely gets above 3000rpm.

Bear in mind that the advertised fuel economy is 9.9L per 100km.

The last tank calculation has been 44.5 litres for 270 km which equates to 16.5 L/100km.

Now when the car was new, I accepted that maybe it was related to the car being in its first 1000km but this has been the way it has been since the beginning. Fuel economy of 15L/100km or slightly worse.

Best we have had is about 12.5 L/100km on a weekend trip that had a bit of freeway and twisty moutain driving.

Now I rang up our toyota dealer to discuss this and whether a bit of a look to see if the engine was in tune was warranted, and they said well, 16L /100km is not far off what they'd expect ( I'd love them to say this to a new car buyer) for a car before its first 12 month/15000 km service. He said then there will be an oil change and we should get better.

However from reading the other threads with people getting sub 10 readings (granted often on the highway), I'm starting to wonder if everything is OK with our car?

Does anyone out there own an Aurion for which they are driving mainly in the city without much freeway driving with whom we can compare. What do people think? Is this within the norm and we should just put up with it until 12 months service???

Another Presara here, on a trip from say Sydney to Canberra and back I can average 8l/100km. Around Sydney with 50% slow motorway I get about 11litres/100k or better. You really do sound like you have a serious problem?

[Blinkybill]

Do you believe the cars fuel usage to be wrong? Even with a 10% error at 5.7l/100 it would still only add 0.57 to the displayed usage (still a very impressive number 6.3l/100). This error would be extreme. If you believe it is wrong at the beginning of each tank why would it be any more accurate at the end of the tank? Everyday when I travel home from work the usage will drop 1 - 1.2 l/100 mainly because there is a lot of downhill (goes back up again next day due to hills), this regardless of whether the tank has just been filled or the warning light is on. Do we all fill the tank to the same level every-time? What is the legally allowable error from the petrol bowser? What is the expansion rate of fuel in the tank, does filling it on a cold winter night versus mid afternoon 40 degree summer day make any difference? Are the tires correctly inflated/worn? How accurate is the trip meter or speedo on your car? Obviously the car uses this info to do its calculation, why would toyota go to all the trouble of giving us all these numbers if they didn't believe they were usable for real world driving. When I fill the car and get a cruising range displayed what error should I expect? This number almost always coincides with the low fuel light coming on and at this stage I still have 12 -15 liters left in the tank. Maybe there are too many variables, I think I will believe the car because a calculation involving all these is not for the average guy to contemplate.

I'll just give you some reasons why I think a manual calculation will always be better than your trip computer.

1. The fuel guage.

Fuel guages are notoriously inaccurate. Have a read of this http://auto.howstuffworks.com/fuel-gauge.htm

The car trip computer uses the same system to read the amount of fuel as your fuel guage does and trust me it is not accurate and "linear". Your fuel tank is not a standard geometric shape. If your car is like most cars, the fuel guage takes longer to go down from full than it does somewhere round the middle. This due to the mechanics of the fuel guage sensor and the shape of your tank. Therefore your trip computer will underread your fuel consumption during that time. Obviously this is when it is giving you your miraculous fuel consumption figures.

2. The trip computer.

Have you noticed how all of Tekkyy's readings are always on the optimistic side, none of them showed the computer's reading to be worse than manual calculation. Toyota has a vested interest to make you think the fuel consumption is slightly better than it is. It gives you a warm and fuzzy feeling and keeps you happy with Toyota.

Your other comments, yes I think your fuel tank should click off the fuel pump at the bowser at the same level of fill every time you fill up. Yes I think that the calibration of fuel bowsers is fairly accurate. It is regulated, I think, just like the scales at Coles which measure your vegetables. How often it is checked I don't know.

I don't have a trip computer on my Aurion, but I know from a Mazda I own that even with daily identical driving, for the first 100km or so, the trip computer may give me a fuel reading of 6.8L/100km, but by the end of a tank the fuel economy will always be about 8.0-8.3 on the computer and closer to 8.5L manually calculated. I see that also with the fuel guage hardly moving off full for the first 100km but then falling more steeply.

If you don't believe me, please do try the manual method ie fill to 1st click, reset tripmeter. Refill again to 1st click after your first 75 km and calculate your fuel economy, litres divided by km travelled then multiply by 100. It won't be 5.0. I'm guessing closer to 7.5-8.5.

I stand corrected if you do this and it's different.

[tekkyy]

its a modern car right?

I am hopefully the trip computer reports from injection values rather than fuel guage

the fuel guage is really bad

but who knows

my results show an error

but as I said I am trying to blame it my petrol filling skills

eg.

49.36L 382km 12.92L/100km (report 12.6L/100km)

+2.0L ---> 12.40L/100km

-2.0L ---> 13.45L/100km

however with the error being negative on average

maybe...oil leak?

in another of those "save petrol" articles it recommended us not to fill past the first click

(something like overflow pipe leaking when you go on a bend)

in the past I fill to second click

not going to do that anymore :D

[fuel miser]

See attached picture straight from the 2GR-FE manual as to how the consumption is calculated.

The variable resistor in the fuel tank is only feed to the fuel gauge - it triggers the resetting and beginning of the calculation. The calculation is performed on fuel used by injector #1 and distance traveled as measured electronically.

The car has a return-less system whereby the fuel is pumped up to set pressure and maintained there by turning the pump on and off. As the car knows how long it has the injector open it knows how much fuel is being used - very accurately.

In con-junction with vvt, emission sensors, air flow, air temp, throttle position, speed and many others I think the car knows exactly what it is doing and what it takes to get the job done.

Filling to the first click is probably the most inaccurate way of calculating fuel consumption. Who has had the fuel trigger trip after inserting it into the tank and grabbing a big handful of trigger. Everyone say out loud "ME"

Edited October 5, 2008 by fuel miser

[VF-X]

4.9L/100KM? Maaannnnn...U r on ur Ticket to the Hybrid World...Even Prius owners with 4.4L/100KM would be shocked If an Aurion could get that kind of readings.

Do manual calculations, coz double checking is always harmless..

[Blinkybill]

See attached picture straight from the 2GR-FE manual as to how the consumption is calculated.

The variable resistor in the fuel tank is only feed to the fuel gauge - it triggers the resetting and beginning of the calculation. The calculation is performed on fuel used by injector #1 and distance traveled as measured electronically.

The car has a return-less system whereby the fuel is pumped up to set pressure and maintained there by turning the pump on and off. As the car knows how long it has the injector open it knows how much fuel is being used - very accurately.

I'll stand corrected on that point.

You do wonder though if it has such an accurate way of measuring fuel consumption why that doesn't tie into the way it records residual fuel in the tank rather than the inaccurate resistor.

Given that your trip from Mount Victoria to M4 is a signficant downhill stretch perhaps your figure is closer to the mark.

I will raise up a few points though.

Statistically, if you thought filling up to the 1st click was inaccurate, you'd expect the reading of litres used to go both ways. Sometimes better sometimes worse. Given that Tekkyy's manual fuel consumption is only one way (always worse than the computer), I'd say there is a trip computer error there too.

Anyway, all of this goes to say, as the last poster said. There is no harm in you one day verifying on your downhill stretch during first 50km of your trip with a manual calculation. Do it one day and perhaps we'll add to our investigation.

[DJKOR]

Okay. Look; there is only one real way to settle all the arguing. DO A MANUAL CALCULATION. I can't car less whether the trip computer on the Aurion is a work of art or not; I'm not going to rely on it for close to accurate.

I say we keep this thread running and you can keep posting trip computer readings for comparison, but at the same time, we start another thread where you can post your manual calculations for real accuracy. On a side note, when I do a manual calculation, I run the car till it says empty (and 0km cruising range) and then drive it an additional 80-90 km to make sure I'm close to 'true' empty.

[fuel miser]

I will provide some info next time I refill the tank.

[insi]

I run the car till it says empty (and 0km cruising range) and then drive it an additional 80-90 km to make sure I'm close to 'true' empty.

DJKOR, when you reach 0 on cruising range, you still can drive around 50km more?

and when the fuel warning turn up, can we still drive around 50km?

I don't dare to test it hehe...since I don't have roadside assist in case it is really empty hehe...

[Speedz]

Yeah you still have about 50km range in reserve before the tank is really empty... all cars are designed that way...

[fuel miser]

Ok just filled up - here goes

the car was reporting 8.9l/100 with 505k's travelled (160k's still estimated left)

the bowser first trip (actually second as first was at 12.19l) was at 44.43l.

8.9 x 5.05 = 44.945 litres as per the car

44.43 litres from bowser

difference 0.515 litres

0.515 / 5.05 = 0.101 l/100k's

I still think the first click method is more flawed that the car method(but both similar on this occassion), but I will continue to update when possible.

[fuel miser]

When the initial fuel consumption came up after refill with minimal distance travelled was 28.2 l/100 (estimated tank range 687 k's). Travelled home through town stopped at shop then home -distance travelled 4.5k's fuel consumption had dropped to 10.2 l/100. A large change in a sort distance no doubt about it but I see this quite often.

Edited October 6, 2008 by fuel miser

[tekkyy]

You do wonder though if it has such an accurate way of measuring fuel consumption why that doesn't tie into the way it records residual fuel in the tank rather than the inaccurate resistor.

but then you don't want to judge fuel tank base on fuel consumption because of thngs like oil leak

I say we keep this thread running and you can keep posting trip computer readings for comparison, but at the same time, we start another thread where you can post your manual calculations for real accuracy.

there's a few ways to organise this

we could have

*fuel economy trip computer

*fuel economy manual calcuation

or

*fuel economy results

*fuel economy techniques

or

*fuel economy advice

(one mega experiment with posting of results and techniques side by side

[v8toy]

i have yet to do a manual calculation but when i fill my tank i fill it right to the top at the cap yes i know it has a overfull pipe etc etc but my thought is if i fill it like this evertime it has to be spilling the close to the same amount out everytime aswell.

so i just did a trip on the weekend to katherine nt from darwin nt.

Distance oneway - 315kms

Time of day - 8pm till 11pm

Temp - 23 degrees (according to car outside temp gauge which i know is close to being right)

Speed- Between 100 - 120km/h

Terrain - Rolling hills

Driving Habit - Easy on throttle, no sudden braking (luckily some big cows up here)

Load - 1x 6x4 quad trailer with one quad approx combined weight of 900kgs, Boot fully loaded with gear bags x2 (had to slam boot lid), back seat fully

with 1x child and ther bike gear plus 1x driver and passenger.

Started off with a fuel reading from the display with 13.3l/100km by the time i had reached katherine had gone down to 10.7/100km did not once climb up in reading always going down.

On the way home.

Distance oneway - 315kms

Time of day - 1:30pm - 4:45pm

Temp - Started at 40 degrees and went down to 35 halfway home

Speed- Between 100 - 120km/h

Terrain - Rolling hills

Driving Habit - Easy on throttle, no sudden braking

Load - 1x 6x4 quad trailer with 2 quads one approx 160kgs and other approx 40kgs (kids quad) combined weight of 950kgs, Boot fully loaded with gearbags x2 (had to slam boot lid), back seat fully

with 1x child and ther bike gear plus 1x driver and passenger.

Stated off with a fuel reading from the display again with 13.8l/100km by the time i reached darwin had gone down too 10.5l/100km again did not once climb up in gfuel readings.

so result is i was expecting the heat to play a part in fuel consumption but it didnt seem to bother it and air con was on middle settings on the way down and flat out all the way home again didnt seem to affect it to much

i know its not a manual calculation but i believe its still reasonably accurate but next time will test properly.

also on the note of distance to empty for when the fuel light comes on i drove a further 95kms b4 it stopped after eading 0 kms to empty and fuel light on again towing the same trailer and load

thats my two bobs for a while

[Fidzeh]

I LOVE my Aurion!

Drove to Sydney and back I had accomplished 6.4L/100KM, I never thought it would get that low and also got 690KM worth of fuel xD

That was done on BP Ultimate petrol.