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How Do I Work Out Mpg?


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Hi folks,

As i filled my IS up on thursday I decided to zero the trip and work out my mpg.

I had an initial journey of around 210 miles ( Leicester - Warrington ) and a couple of commutes to work and some stop start.

I just don't know how to work my MPG out ? please see figures below :)

315.1 Miles

37.56 litres - to top her back up

(£44.28) cost @ 117.9 a litre

hope you can help me out people?

for the whole motorway journey i didn't exceed 60mph - so lets see if it makes a difference

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Hi folks,

As i filled my IS up on thursday I decided to zero the trip and work out my mpg.

I had an initial journey of around 210 miles ( Leicester - Warrington ) and a couple of commutes to work and some stop start.

I just don't know how to work my MPG out ? please see figures below :)

315.1 Miles

37.56 litres - to top her back up

(£44.28) cost @ 117.9 a litre

hope you can help me out people?

for the whole motorway journey i didn't exceed 60mph - so lets see if it makes a difference

Divide Litres by 4.544 to get gallons. In this case gives 8.266 Gal, so 315.1 miles divided by 8.266 Gal gives 38.1 mpg. Wonderful if that were true, but I think something may be wrong with either the litres you show or the distance? The IS200 isn't usually that good. I would repeat it. Brim the tank, drive a known distance (from the trip or main Odometer) until most of the fuel is gone, then use the litres needed to brim the tank again. Even doing it this way you get a few percent error due to inaccuracies of the Odometer and forecourt pumps but it is the nearest you will get to the true figure.

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Hi folks,

As i filled my IS up on thursday I decided to zero the trip and work out my mpg.

I had an initial journey of around 210 miles ( Leicester - Warrington ) and a couple of commutes to work and some stop start.

I just don't know how to work my MPG out ? please see figures below :)

315.1 Miles

37.56 litres - to top her back up

(£44.28) cost @ 117.9 a litre

hope you can help me out people?

for the whole motorway journey i didn't exceed 60mph - so lets see if it makes a difference

Divide Litres by 4.544 to get gallons. In this case gives 8.266 Gal, so 315.1 miles divided by 8.266 Gal gives 38.1 mpg. Wonderful if that were true, but I think something may be wrong with either the litres you show or the distance? The IS200 isn't usually that good - even they only quote 36.2 for extra-urban. I would repeat it. Brim the tank, drive a known distance (from the trip or main Odometer) until most of the fuel is gone, then use the litres needed to brim the tank again. Even doing it this way you get a few percent error due to inaccuracies of the Odometer and forecourt pumps but it is the nearest you will get to the true figure.

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Divide the number of litres by 4.54 to get it into gallons

37.56/4.54 = 8.27 Gallons

Divide the number of miles by the number of gallons

315.1/8.27 = 38.1 mpg

Thanks for that. :)

thats very good, im impressed. Altho for 210miles of the journey I sat at 60 behind a lorry on the M6, i arrived in warrington relaxed and calm - usually i don't hang about on the motorways - but it jut goes to show how much of a difference it can make

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that 38 MPG is unbelievable. how come I never seen anything more than 25-28 on mine?

were you driving 50 on the motorway flat?

suggest you work an average out over a month.

total mileage / (total amount in litre/4.544)

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that 38 MPG is unbelievable. how come I never seen anything more than 25-28 on mine?

were you driving 50 on the motorway flat?

suggest you work an average out over a month.

total mileage / (total amount in litre/4.544)

I know some of you wont believe it, but i know those are the figures and have been as accurate as possible.

Like you say, i would like to do something similar again at the end of the month.

yes i sat behind a lorry the whole way, between 55 and 60 mph. I had an indicated half a tank (well one notch under) left

this includes traffic lights and stop start driving too! but i am very concious now about mpg, im not one of these that straight from accelertor to the brake, coast it in gear etc:)

Felix is yours an auto?

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My daughter drove us (4 adults) from Liverpool to Stratford upon Avon last year. She cruises along between 60-70ish and never accelerates hard and brakes gently. She got 37 mpg. Stark contrast to my urban driving of 24mpg.

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on highway I have also had 38mpg.

few tips are:

be gentle with throttle

if you have manual gearbox, use gears to slow down and dont let engine to idle in netural while coasting

see as far forward as possible to prevent hard stops.

if you see a red traffic light, let go accelerator, if you see someone far ahead slowing down, let go your right foot.

owerall i get ~28mpg on each tank

best i have made on one tank is 890km = 553 miles from a full tank to empty stop.

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To be honest guy's i can get 32mpg all day long and i have had 38-40 on a trip from Leeds to Manchester on the M62.

Try doing this and see the diffrence,when cruising on a motorway or open road get to the desired speed and look at your mpg gauge on the dash,now back off the loud peddal a little bit and you will see the mpg gauge move considerably and you will still maintain the speed you were at.

I have just been camping in the North Yorkshire moors with 2 adults 2 kids and the boot rammed full of gear,to be honest the IS is shocking at climbing hills without booting it and changing gear alot and i still got 28-30mpg all the time.

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