How To Calculate Your Car's Fuel Economy?


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Could anybody tell me how to keep track of the mileage in cars. Suppose i have around 5 litres of petrol filled in my car. Now i need to know how much kilometer it is giving for one litre of petrol. How to calculate? Please help. I am using maruti alto LXI.Any valuable help is greatly appreciated
 

Akash

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Re: How to Calculate Car's Fuel Efficiency?

The best way to calculate the fuel efficiency of the car is Tank to tank or full to full method.

To begin with, fill up the fuel tank up to the brim and note down the odo reading(say Akm); or set Trip meter to 0. Drive your car in the manner you really do and once the fuel meter tends to get near the empty mark(or even half), refill the tank to the brim and note down the amount of fuel(say Xlts) which gets into the tank. Also note down the odo reading at the time of filling(say Bkm).
Subtract this reading with the previously recorded reading(at the time of filling the fuel).
Divide the result(B-A) by the amount of fuel consumed(taken in when you filled this time).
That is, FE = [(B-A) / X]kmpl.
The figure obtained is your real time fuel efficiency:smile:.
 
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Re: How to Calculate Car's Fuel Efficiency?

+1 method suggested by Akash. This is the most ideal way to do it. Couple of points i would wish to add.
> Alto Lxi does has a trip meter. Hence as suggested by Akash, set the trip meter to ZERO when you fill the tank full.
> Try to fill petrol from the same fuel station when you want to keep a track of mileage.
> Repeat the tank full method for @ 3-4 times and keep a track of mileage. Then obtain the avg mileage which would be the most closest to accurate mileage
 
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Re: How to Calculate Car's Fuel Efficiency?

+1 to Akash's reply. That is the method i follow too!


And also like Carfreak said i always fill up at the same bunk and even from the same pump and nozzle!


But once again the same doubt! Is it advisable filling it upto the brim? I always stop it with the auto cut-off.
 
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Re: How to Calculate Car's Fuel Efficiency?

How can i calculate mileage without using Full to Full method?
 
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Re: How to Calculate Your Car's Mileage?

Well if your car has a reserve indicator then fill up for Rs.500 or so. Reset the trip meter and note down the number of litres. Then when the reserve indicator comes up again fill up again , and divide the number of KMS with the number of litres to get an highly approximate figure. But i tell you this is not a good method and it's highly inaccurate.


The best method is tank full to tank full method.
 
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Re: How to Calculate Your Car's Mileage?

Well if your car has a reserve indicator then fill up for Rs.500 or so. Reset the trip meter and note down the number of litres. Then when the reserve indicator comes up again fill up again , and divide the number of KMS with the number of litres to get an highly approximate figure. But i tell you this is not a good method and it's highly inaccurate.


The best method is tank full to tank full method.
I have never seen car with reserve indicator. Which car has that. Is it like in the bikes reserve tap or something like that ??
 
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Re: How to Calculate Your Car's Mileage?

All modern day cars have reserve indicator or should i say low fuel indicator. I have seen it in i20 , Aria and Vento.
 
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Re: How to Calculate Your Car's Mileage?

Tankful to tankful is the best and most reliable method. By the way, my i10 automatic gave 15.5 km/l in 100% city driving [surprise] with 80% AC on. Used shell unleaded petrol.
 
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Re: How to Calculate Your Car's Mileage?

We dont have to wait till the mark reaches half or empty to refill.. Drive for some 100 or 200 kms after refilling and then fill again to tank full (or brim, whichever was done first). Now the quantity of fuel required Vs distance covered gives the mileae. This can always be an approximate value cos the first few may have consumed more or less due to traffic/tire pressure/load on tha car and these factors may vary for the whole distance covered having variance in mileage.
 
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Re: How to Calculate Your Car's Mileage?

I have an alto.Filled 500rs petrol,ie 7.36L here,now ran 47kms with A/C,still needle bit above the red line.waiting for the needle to come down.
 
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Re: How to Calculate Your Car's Mileage?

The float mechanism in the fuel gauge will not be accurate always. Especially when it is near the full tank mark. you can notice sudden drop once the needle crosses the half way mark (when on its way to empty). This has a resistor setup controlling the needle movement and always it can be an approximate value only.
 
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Re: How to Calculate Your Car's Mileage?

I have an alto.Filled 500rs petrol,ie 7.36L here,now ran 47kms with A/C,still needle bit above the red line.waiting for the needle to come down.
Please do not check the mileage the way you are checking it because you never know whether the needle is correct or not. Or there may be some play* in it which might restrict it completely coming down before it is too late for you. Read 3rd and 4th posts at the beginning of this thread. Akash and Carfreak has suggested the exact way to calculate the avg.

All the best.

* By play I am being generic here. Do not kick me for that[lol]
 
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