Measuring Fuel Economy

Submitted: Monday, Aug 04, 2008 at 01:05
ThreadID: 60460 Views:2594 Replies:6 FollowUps:3
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Hi, I am wondering how you can measure the fuel economy of a vehicle (01 GU TD in particular) i read all the time that people have better or worse fuel economy depending on their driving and i want to know how to get such an accurate reading for my up and coming trip?

Thanks

Mike
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Reply By: Dolphin38 - Monday, Aug 04, 2008 at 01:32

Monday, Aug 04, 2008 at 01:32
Mike,

Pretty easy...

You first need to start with a full tank of fuel and zero your trip meter when you fill up. Next time you fill up, record the amount of fuel you put into the tank to fill up and also note the distance travelled on the trip meter.

Then get out the calculator.... divide the number of km's driven by the amount of fuel you put in the tank to fill and that will give you km/ltr. eg: 700km driven, 59.2ltr to fill up = 11.82 km/ltr.

To get ltrs/100km, just divide 100 by your km/ltr figure, eg: 100 divided by 11.82 = 8.46 ltrs/100 km.

Hope this helps.

Cheers,
Guy
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Follow Up By: Notso - Monday, Aug 04, 2008 at 08:19

Monday, Aug 04, 2008 at 08:19
one other little thing,

Check the accuracy of your odometer. They can be out by quite a bit if you have changed tyre sizes, My GU was about 5% out on the stock tyres.

You can check it with your GPS if you do it on some straight and level road. Or use the odometer check strips on some of the highways.
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Follow Up By: pjd - Monday, Aug 04, 2008 at 12:17

Monday, Aug 04, 2008 at 12:17
to be spot on you need to use a gps & check distance traveled
with ltrs used try this web site
http://www.dropbears.com/u/utilities/fuel_efficiency.html
my gu with 285/75/16 tyres = 1.13 klms by gps & 1klm on odo
so every 100 k's i do its realy 113 & that adds up over a tank of fuel
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Reply By: tryonreef - Monday, Aug 04, 2008 at 05:56

Monday, Aug 04, 2008 at 05:56
Try this link Mike and use the calculator...
Fuel Economy Calculator
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Reply By: Cape York Connections - Monday, Aug 04, 2008 at 06:55

Monday, Aug 04, 2008 at 06:55
I feel that to get a accurate reading you cant because depends on wind direction strength of wind time of day hot or cold,road surface etc etc etc.
You can get and average.
My average is 14 litres per hundred. that's on diesel 60 series turbo in all conditions.


All the best
Eric
AnswerID: 318908

Reply By: Gone Bush (WA) - Monday, Aug 04, 2008 at 12:36

Monday, Aug 04, 2008 at 12:36
There are many ways to calculate the fuel economy.

To get litres per 100ks I do it this way:

say 70 litres were used to travel 475 klms. Just put the decimal point two spaces to the left in the distance figure ie, 4.75

Then divide 70 by 4.75 = 14.74 litres per 100ks.

If you want to convert to miles per gallon:

Divide 283 by 14.74. = 19.2 mpg

If you were using klm per litre then multiply your figure, say 7 k/litre by 2.83 = 19.81 mpg.

It's handy to know that 7k/l and 14l/100k are both near as can be to 20mpg.

cheers

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Reply By: Mike GU - Monday, Aug 04, 2008 at 14:03

Monday, Aug 04, 2008 at 14:03
So to find out how many liters used you need to fill up, record distance travelled and then fill up again and that figure on the pump at 2nd filling will be your fuel used for that trip, and use one of the formulas provided?
Got it.
By the way whats is the average consumption for a 01 GU patrol wagon with roof racks running stock rubber?

Thanks for the help everyone!

Mike
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Follow Up By: Goona - Monday, Aug 04, 2008 at 20:35

Monday, Aug 04, 2008 at 20:35
Mike,

For a 3lt My mate is getting around the 10lt / 100 on the hwy with 285's and full rack on. Aound town it is about 12. Loaded and towing a caravan it it around 16. My Patrol 4.2lt is currently getting 14lt/100 but that is towing a Goldstream camper with tinnie on the roof and running 285's. I also have gas in this at 3lt per 100.

Goona
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Reply By: Nomadic Navara - Monday, Aug 04, 2008 at 22:50

Monday, Aug 04, 2008 at 22:50
It is difficult to fill the tank to the exact amount each time. For a better estimation of fuel consumption it is better to use the distance travelled over several fills of the tank.

PeterD
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