How do you keep track of MPG?

Conanius

Conanius

Conanius

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As topic really..

I've just started using Fuelly on the iPhone after starting a new job about 35 miles away. Mainly, to see if my man maths had been remotely accurate.

I'm driving a 2004 Discovery 3 HSE with the 4.4 V8 Petrol 6spd Automatic, and Fuelly reckons that over 1656 Miles I've averaged 18.59 MPG, with a best fill of 20.92

I think I can get it a bit higher, maybe to 21-22mpg consistently, as I'm learning better routes and becoming more 'aware' of managing my fuel economy. It's a combination of NSL Dual Carridgeways and country lanes, and lots of hills (joys of the Cotswolds).

I'd worked out that I thought I could average 16mpg, and with that, I'd have been happy.

Interestingly my trip computer is consistently within 10% of the Fuelly figures, which I guess is about spot on for the 'usual' difference between the two.
 
Fuelly is the best method I've found, used it for several years :)

That said I only keep track of my daily, I'd rather not know what the mpg of my 350Z is!
 
I generally just leave the obc counting up over thousands of miles. Wildy innacurate but consistently wildly innacurate to give an idea of when its improving/declining
 
I use an app called mileage which I have used for about 4 years.

This has given a total average of 37 for the 530d and 26 for the 530i.
 
I use an app called Fuel Log for Android (i have long since ditched my iPhones, but i used Fuelly on those), its pretty much the same thing.

To be honest though i dont really use it these days, as you say the car computer is pretty accurate, and to be honest you use what you have to use!

My fuel economy is near identical to yours by the way (4.4 V8 Range Rover), i can get it up to around 23-24 on a run :)
 
I'm surprised anyone would obsess over mpg when driving a 4.4l v8? Did you not know what you were getting yourself in to before you bought the car?
 
I use fuelly too, but not as an app, I just use the site.

Only been using it for a couple years though, before that I was manually calculating to get the actual consumption.








It is worth noting that I ran my Range Rover on LPG though. So the 13.5 mpg was actually closer to the equivalent of 27 mpg, which I was pretty happy with. It would do around 20 on petrol though, which was also reasonable enough.

pepsilol said:
Do people really care this much? I only check the MPG after the first couple of tank fulls on a new car and then it's business as usual..
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Clearly I do, lol. I first started using it with my Audi A4 Black Edition, as it was sooooo terrible on fuel, it did nothing by way of offsetting some of the purchase price with increased fuel economy. Not that it mattered that much in the grand scheme of things, but was enough for me to reject the car.
 
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pepsilol said:
Do people really care this much? I only check the MPG after the first couple of tank fulls on a new car and then it's business as usual..
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Adam said:
I'm surprised anyone would obsess over mpg when driving a 4.4l v8? Did you not know what you were getting yourself in to before you bought the car?
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I'm doing it out of interest really. I'd said I would be delighted to manage an average of 16mpg in the car, so the current figures are a pleasant surprise. Seeing a major dip also could point to an issue that needs fixing.

So yes, I knew exactly what I was taking on, hence the 2.5k 'oh crap' fund on top of expected costs.
 
Using an app called road trip on my iphone, nice interface and does the job fine.

Currently reading 26.8 on the 350z and 34 on the civic :( - damn my across town commuting

Hawker
 
Ive always found my obc to be pretty accurate if not the same as working it out from how much ive filled up with vs miles traveled. Obviously reset each time after a fill.
 
I used phone apps for my old cars which didn't have a MPG readout. Used it on this skoda just to check how accurate the MPG readout was. It's always accurate to 1mpg so I just don't bother with the phone app now.
 
I just log it all with Fuelly.com (the website) as a matter of interest really. I don't actually care too much what MPG I get as I don't need a car so it's pure fun only. Fuel costs what it costs and I use what I use, if I get good mpg great, if I get poor mpg, no bother.

This was the E30:


and this is the Golf:




I find it interesting to see the MPG especially after doing work on the car and trips etc. For example, my best in the Golf was my last fill up at 33.4mpg and that tank was used to blast around country lanes. :D

E: oh and the MFA is fairly inaccurate really given this is what my average is for the life of the car (since I've had it):
avgmpg.jpg
 
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theone8181 said:
Ive always found my obc to be pretty accurate if not the same as working it out from how much ive filled up with vs miles traveled. Obviously reset each time after a fill.
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A lot of people have always claimed that this method is more accurate than the OBC, me included.

However, I was thinking the other day - how is that so? The OBC must calculate the average using simple miles driven/fuel used figures. But why would it be more accurate to do it yourself? Surely you are using the same mileage figure taken from the OBC? And I would have thought the OBC would have perhaps the most accurate idea of how much fuel has been used because it must calculate and control fuel use constantly.

Anyway, to answer the OP - I used to check every single fill up using the calculator on my phone. My car now has an MPG readout and a couple of months ago, I stopped bothering to check every fill. The readout appears perhaps 1-2MPG more optimistic than checking manually so I just stopped bothering and rely on that.
 
^^ The error introduced within the OBC is from the fact that the car can only estimate fuel usage based on fuel pump data and conversion factors from that.

By contrast a human can see how much fuel is actually used with near perfect accuracy.
 
Conscript said:
However, I was thinking the other day - how is that so? The OBC must calculate the average using simple miles driven/fuel used figures. But why would it be more accurate to do it yourself? Surely you are using the same mileage figure taken from the OBC? And I would have thought the OBC would have perhaps the most accurate idea of how much fuel has been used because it must calculate and control fuel use constantly.
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Depends on the maths behind the calculations done by the car completely. You can adjust the values on quite a lot of cars if it's inaccurate.
 
Jez said:
^^ The error introduced within the OBC is from the fact that the car can only estimate fuel usage based on fuel pump data and conversion factors from that.

By contrast a human can see how much fuel is actually used with near perfect accuracy.
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Well, that's kind of what I was getting at...I would have thought that the car's fuel pump data would be perhaps the most accurate. At least as accurate as reading off the filling station pump after brimming the tank.

But then people always seem to find the manual method gives quite a different readout, me included.

InvaderGIR said:
Depends on the maths behind the calculations done by the car completely. You can adjust the values on quite a lot of cars if it's inaccurate.
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I didn't know that. Mine only appears to vary from the manual check by 1-2MPG, so I now just rely on it.

As someone else said, it's not really to know what the MPG is, just use it to keep an eye on any unusual trends.
 
My car has no onboard so I started using fuelly earlier this year after not entirely believing my once in a while calculation. The ability to track over time is good as pump click off and the full tank may not be exact every time.


What I don't like about the site is the poor car by car breakdown if you want to look at other cars. For example try to look for a current Panda Twin Air or Fiesta 1litre
 
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