Fual costs

[Vincenzo]

Greetings

I have a manual AU 111 XR6 that I will be starting a build thread on in the next few days. Prior to that though I have been experimenting with fuel and it's effect on mileage. I usually have to put in about 60 litres

Here in Darwin we pay $1.50/litre for 91 ron unleaded
(this gives me 450km around town and 550km on a trip)

We pay $1.60/litre for 95 ron -
(this gives me 500km around town and 610km on a trip)

$1.62/litre for 98 ron with 10% ethanol and
(this gives me 580km around town [60 litres] and 710km [61 litres] on a trip)

we pay $1.82 for BP Ultimate 98 Ron - no test drive yet

As a pensioner I can justify an extra $6 per tank for better milage but an extra $18 per tank I would need to get at least 810km to 820km on a trip and about 660km to 680 km around town.

We don't have the weekly swings in price you get down south so shopping around is out of the question so what is the consensus - would the above mileage seem do-able


Cheers and thanks for reading


Vincenzo

[Vincenzo]

Also meant to ask - do you have a 32cpl difference between 91 ron and 98 ron where ever you are?

[ronwest]

Originally Posted by Vincenzo

would the above mileage seem do-able

660kms around town? No way...

810kms on a trip is do-able (not for me tho). My brother consistently got between 800 and 850kms on a trip. He drives at around 90kph, so the trade off is time (and punch ups with other motorists ,lol)
Best he's ever done around town (Glen Innes) is 545kms. I get around 400kms around town and 600 to 650ish on a trip (S3 F/Ghia)

Our fuel prices (Bris) fluctuate wildly. I'm just not sure if 32cpl is the average fluctuation between 91 and 98.

[Professor Farnsworth]

i'm already surprised by the huge variations in mileage you get with 91-85-e10. It usually takes several tanks to see any sort of benefit with my cars, and even then it's nowhere near what you get. If you get that sorta benefit from 95, stick with it.

[Mr Hardware]

I've owned three AUs now and have supervised a fleet of 20-odd over a 3 year period, and covered well over 100,000klms in various AUs.

I'm not saying that your claims are untrue, i'm just saying your AU would be the only AU i've ever come across to have such varied fuel consumption behaviour.

In my experience AU's simply don't care what kind of fuel you feed them - they just drink it like a 747 on take-off regardless.

[4ford]

quote from "Mr Hardware"...

"In my experience AU's simply don't care what kind of fuel you feed them - they just drink it like a 747 on take-off regardless."

I beg to differ...my AU2 Fairmont 6 responds noticeably different with regard to the grade of fuel I buy.
With that in mind, I run it on 95 ron most of the time.

On a slightly different note, you happened to mention a 747 in your post, which reminds me of a point which seems to be relevant here, with regard to fuel consumption.

ALL commercial aircraft, from Cessna 310s to B747s, tightly regulate the quantity of fuel they carry purely to limit the amount of unnecessary weight they carry, since they don't want to be using more than necessary fuel to simply carry additional fuel they don't need.

They carry only enough to get to the intended destination (taking the enroute winds into account), plus enough fuel to get to an alternate destination, plus enough for about one hours' flight time, no more!

In short sector flights, like up/down the east coast of Oz, if the fuel costs are significantly higher at the destination, then they will carry return fuel, since the extra cost of uploading fuel exceeds the cost of carrying it!

This all gets somewhat complicated, but the point I'm trying to make here, with cars the same rules apply on a somewhat smaller scale.
So, why fill the tank right up, and have to cart around a very heavy full fuel tank, costing you fuel to haul it, when there is a gas station on every corner!

With my aviation background, and unless I'm driving long distance, I only ever fill the tank to around half, and that way not turning my car into a tanker!

Works for me!

[Vincenzo]

Originally Posted by ronwest

660kms around town? No way...

Our fuel prices (Bris) fluctuate wildly. I'm just not sure if 32cpl is the average fluctuation between 91 and 98.

Thank you for the response - the best mileage I have got was my last tank around town of 580km for 60 litres. The 660km I refer to is what I would need to get to justify paying $1.82 / litre.

As for cost of fuel our prices have been steady for at least the last two to three months.

[Vincenzo]

Originally Posted by Professor Farnsworth

i'm already surprised by the huge variations in mileage you get with 91-85-e10. It usually takes several tanks to see any sort of benefit with my cars, and even then it's nowhere near what you get. If you get that sorta benefit from 95, stick with it.

My mileages are not one off tanks. They are done over a period of a month or more ( three to four tanks). Having said that the 710km for the 98 ron with 10% ethanol is only two tanks.

[Vincenzo]

Originally Posted by Mr Hardware

I'm not saying that your claims are untrue, i'm just saying your AU would be the only AU i've ever come across to have such varied fuel consumption behaviour.

In my experience AU's simply don't care what kind of fuel you feed them - they just drink it like a 747 on take-off regardless.

Thank you for your scepticism and honesty. I can only repeat what I consider to be real world figures. I only joined the forum in july this year and have been quite surprised at the various figures I've seen people quoting in their posts. It made think "do I have a really good engine or is it my refined style of driving." I have been teaching people to drive for 35 years.

[Mr Hardware]

Well i've always found fuel economy to be an extremely illusive thing. There are so many factors surrounding what makes a good run vs what makes a bad run - not just speed, but heat, wind, surface, gradient, weight, humidity etc.

My economy always fluctuated by about 10% doing 'the same sort of driving' - until I moved offices and had the exact same 68km trek each way to work. Only then could I tell you pretty much down to about 10k how many kays i'd have in a tank. Filling up with 500L of LPG a month forces you to monitor your usage carefully!

[dwnsnow]

hey vincenzo that pretty good for my thinking i also am in darwin have s3 xr8 feed it 95 usually at 350 km @ 50 ltr but then i didnt buy it for fuel economy alot better on the hiway 10 ltr per 100 k and around town at 14.5 ltr per 100 its better than my ba wagon 4ltr wich is about 15 ltr
per 100k and not as much fun to drive as the au

[Vincenzo]

Originally Posted by Mr Hardware

Well i've always found fuel economy to be an extremely illusive thing. There are so many factors surrounding what makes a good run vs what makes a bad run - not just speed, but heat, wind, surface, gradient, weight, humidity etc.

When I do my highway test I fill up at the same service station in the CBD - then it is a trip down the highway starting in a 40 kmph zone then continuing out of town to Katherine - grab a cup of tea and head back to Darwin - approx 650km return journey.

[Vincenzo]

[QUOTE=dwnsnow]

thanks - been a few thousand years since we've had snow in town.

Keep an eye out for my build thread probably starting on the weekend.



Cheers Vincenzo

[ronwest]

Originally Posted by Vincenzo

The 660km I refer to is what I would need to get to justify paying $1.82 / litre.

Yeah, I was aware of that. You're already getting the best mileage per tank that I've heard of.
Give it a go for a couple of tanks. Report back and let us know how you go.

[Vincenzo]

Greetings

Just completed a trip down the track and back running on 98 ron. It used 2.5 litres (58.5 litres for 650 km) less than running 98ron with 10% ethanol.

So my conclusion is that as someone previously suggested, it would seem more financially viable to run 95 ron than either of the the two 98 ron fuels - 95 is at $1.60/l 98 with 10% is $!.62/l and 98 Ultimate is $1.81/l.

I have just upgraded the exhaust from block to tail pipe so I guess I will have to start all over again AND maybe wait till I get a tune for it this time.

Cheers to all

Vincenzo

[rowan194]

I recall a few years ago seeing a noticeable increase in economy with that fancy 98 that Shell sold for a bit, Velocity or something like that? It was marketed with red Ferraris. Back of the envelope said that it was about the same effective cost as a 95 fuel (or was it 91)

The normal 98 fuel didn't make much difference in consumption, it was only that specific Shell fuel that did. They no longer sell it in Vic.

[Mr Hardware]

If you look at it the scientific way, for energy content per litre, the best value for money petrol is always going to be bog stock 91 (non ethanol of course).