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Discussion Starter · #1 ·
Didn't someone mention a good way to calculate your MPG by filling up to the first click at the pump and driving a certain distance then filling again at the same pumpt ill the first click again?

I either read it here or on XPF or MYMGZR but can't find it.

I have tried search, maybes I am being blind, I did have a migraine today afterall! :slap:

The reason I ask is because I don't seem to be getting very good MPG out of my 05 ZR Trophy 105. I expected similar MPG to my fiat brava but think I am failing, I can't tell until I calculate it properly. I know people suggest filling to the brim etc, but I did read about the first click thing on a forum somewhere....

Cheers

John
 

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here you go mate...

To calculate mpg accurately:
- run the petrol down to the red marker
- fill it up full
- reset mile counter
- drive till it's on the red again
- fill up full again
- note how many litres you filled back up with
- note mile counter
- use miles covered + litres used to work out mpg (roughly 4.54 litres = gallon)
 

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Discussion Starter · #4 ·
Ok, cool I'll do that next fill..... should I fill to the brim to the point that I can see it and anymore would overflow?

Also where did I read about someone filling it up till the first click on the pump?
 

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aww i dont no mate, i remember seeing that on a thread i put up, and im guessing its til it over flows, thats when its full aint it, i havnt used this idea me self, just fort i would help you out lol.
 

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Discussion Starter · #6 ·
Well theres no prob, I can fill to the brim next time, just while I was filling up on my way home I thought I would stop at the first click as I read something here, probably more accurate to fill to the brim anyway as the chances of getting the same pump again is small.

I will try the way you mentioned, makes most sense.
 

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Does the ZR come with a low fuel warning light? If so, run the car until this bleeps, reset the odometer, put a gallon of petrol in and and basically run it as normal until this goes off again.
 

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Does the ZR come with a low fuel warning light? If so, run the car until this bleeps, reset the odometer, put a gallon of petrol in and and basically run it as normal until this goes off again.
You've got to be joking - it's the only modern car I know of that doesn't come with a low fuel warning light.

Also best way to calculate MPG is to buy a car that has a trip computer in the first place.

Also don't expect good MPG in your ZR105, I wasn't even getting 35mpg under normal conditions.
 

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I thought my rover 25 did,

But found out the hard way that it didnt :(
So did I with a ZR105, ran out of petrol for the first time in my life - on a motorway as well - at least I had AA membership - [insert swear word here] well embarrassed so I was....
 

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So did I with a ZR105, ran out of petrol for the first time in my life - on a motorway as well - at least I had AA membership - [insert swear word here] well embarrassed so I was....
I had a Metro and I never ran out of petrol, what's your excuse? :err:

How did you calculate your 35MPG without a trip computer either?
 

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Also best way to calculate MPG is to buy a car that has a trip computer in the first place.
Rubbish.

just about the only way to accuratley calculate mpg (in the short term) is the method described above. Trip computers are often innacurate and usually report better mpg's than you are actually getting.
 

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Use the method described above. Use the same pump on both occasions, and make sure the car is pointing in the same direction.

Just fill it to the first click. Fuel pumps are designed to shut off so that it leaves a small amount of room for expansion of the fuel. If you fill it up in the morning for instance, right to the brim, and leave it all day in the sun, when you come back to your car, the petrol will be all down the sides and over the floor. Not good.

And why do people need a low fuel light? When the needle gets to the red, fill it up.:rolleyes:

Rich.
 

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Rover 25 1.4 (105) when on the motorway taking it very easy i can get 60mpg, arround town however it can go as low as 25mpg my adverage is about 35mpg.
 

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In the rally car, i roughly average about 20mpg on the road. However on the SW Endurance Rally, i averaged 15mpg for the whole event, but with lots of road miles i think the mpg in the forests was down to about 8 or 9 mpg !!!! All this with a standard 1.4 16v engine
 

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And why do people need a low fuel light? When the needle gets to the red, fill it up.:rolleyes:
Or don't let it reach the red; its not as if we have a shortage of petrol stations over here.

First click should suffice, and I don't see why you'd need to run it to the red first unless maybe you were using different fuel.

Fill the tank til it clicks. reset the odo. go for a drive, refil tank til it clicks.

the longer you drive for before refilling and testing the more accurate the figure you'll get it (as % error will be lower)
 

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In the rally car, i roughly average about 20mpg on the road. However on the SW Endurance Rally, i averaged 15mpg for the whole event, but with lots of road miles i think the mpg in the forests was down to about 8 or 9 mpg !!!! All this with a standard 1.4 16v engine
what mods did you do to the 1.4 engine?
 

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Rubbish.

just about the only way to accuratley calculate mpg (in the short term) is the method described above. Trip computers are often innacurate and usually report better mpg's than you are actually getting.
Not got one in your R45 I take it ?

When you have a trip computer, do manual tests to check for accuracy then you know you can rely on it.

When you don't in your case then just stick to the manual way everytime.
 
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