Don't rely on your MPG reading

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Agent_Trig

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For those of you that quote your MPG figures based on what your DIS is telling you, you should start calculating your MPG properly based on the amount of miles you've done to however many litres of fuel you've stuck in.

I've been using an iPhone app called Road Trip since I got my A3 PD140 back Feb 2011 and the average MPG I've been getting since then is 42.39 which is a lot lower than the 48.9 that my DIS is reading out.

I'm sure there are alternative apps out there for other smart phones and you really need to be filling up your tank to the click otherwise you will never get accurate readings.

Hope this is of some use to ya :)
 
I always thought the computers on VAG cars were generous when it comes to mpg

just calculated my last tank 530 miles from 54 litres with 44.9 mpg and would you believe it my computer said the same!

I wonder if that is a one off though
 
I find my DIS readings to be about right - I don't go to any great lengths to calculate it myself, but when I happen to do the sums it seems about right (27.2 average anyway, so it had better not be much lower!!).
 
In a typical week I get 45mpg true. DIS readout is often around 52MPG! Never had a DIS yet in any of my German cars that is accurate!
 
i did a recent "real time" mpg work out and my car is doing average (of course it varies daily for traffic etc..) to be doing 43.3mpg on my daily commute to work and back , which i think isn't bad for a petrol engine :)
 
This doesn't half worry me when i've got a 1.6 that tells me i'm doing 30 MPG, could get a SUV to do that!
 
at long last someone has spoken the truth about the MPG lies.
MY MY59 1.8 TFSI told me that i did 49MPG but the car seemed to take
up alot more fuel and i thought more like 37MPG.
Agent_Trig said:
For those of you that quote your MPG figures based on what your DIS is telling you, you should start calculating your MPG properly based on the amount of miles you've done to however many litres of fuel you've stuck in.

I've been using an iPhone app called Road Trip since I got my A3 PD140 back Feb 2011 and the average MPG I've been getting since then is 42.39 which is a lot lower than the 48.9 that my DIS is reading out.

I'm sure there are alternative apps out there for other smart phones and you really need to be filling up your tank to the click otherwise you will never get accurate readings.

Hope this is of some use to ya :)
Click to expand...
 
Never trust the DIS or computer in ANY car for this info. Mine is averaging 54mpg on the DIS but the actual figure from brim testing is closer to 48mpg.

Whenever I read a post by someone saying they are getting XXmpg on the DIS I always knock between 5-8mpg off as this seems to be the usual over read. My Golf and my BMW over read by about the same.
 
1inchpunch said:
Never trust the DIS or computer in ANY car for this info. Mine is averaging 54mpg on the DIS but the actual figure from brim testing is closer to 48mpg.

Whenever I read a post by someone saying they are getting XXmpg on the DIS I always knock between 5-8mpg off as this seems to be the usual over read. My Golf and my BMW over read by about the same.
Click to expand...

I do the same when people quote their MPG readings.

Unless they work it out properly by filling up to the brim each and every time, then they will never know the true MPG readings for their car.

Yours is pretty good though mate - 6mpg more than me and we have pretty much the same car. What kind of driving do you do?
 
it can be adjusted via VCDS if your getting over reading from the DIS.
First long trip in mine gave 28.2mpg in the DIS, actual was 27.9 based on a brim to brim with some basic maths, so happy with that.
 
Agent_Trig said:
I do the same when people quote their MPG readings.

Unless they work it out properly by filling up to the brim each and every time, then they will never know the true MPG readings for their car.

Yours is pretty good though mate - 6mpg more than me and we have pretty much the same car. What kind of driving do you do?
Click to expand...

Usual drive is the commute to work. 30 miles each way, roughly half the journey is motorway in rush hour traffic although my route avoids ever getting stuck in traffic unless there is a breakdown/accident/roadworks. The only time I really see the figure affected is if the wind is really bad as about 1 third of the journey is coastal.

Have to say I was surprised your figure was lower than mine, but I guess there are a lot of factors to consider...... main one being that I drive like a granny most of the time.
 
As long as i get 500 miles to a tank I'm not fussed about what the DIS says really.
 
Ive just worked mine out, not sure if its very good or not, dont really know what the average is. i got around 410 miles out of 55 litre tank. Taking into account that i wasnt quite in the red and that the tank wasnt full to the brim I reckon around 38-40mpg. 1.6 Petrol 53 Plate with 65000 on the clock.
 
MurdochA3 said:
Ive just worked mine out, not sure if its very good or not, dont really know what the average is. i got around 410 miles out of 55 litre tank. Taking into account that i wasnt quite in the red and that the tank wasnt full to the brim I reckon around 38-40mpg. 1.6 Petrol 53 Plate with 65000 on the clock.
Click to expand...

That's not an accurate way of doing it I'm afraid.

Here's how...

1 - Fill to the brim and make a note of your cars mileage (not trip).
2 - Drive until whenever you fancy filling up again (doesn't have to be near empty).
3 - Fill up to the brim again and make a note of your cars mileage.
4 - Make a note of how many litres exactly you put in to the brim.
5 - Divide the number of litres by 4.54 and this will give you how many gallons you used.
6 - Now divide the number of miles travelled between the fill ups and you will get your MPG.

You need to do this each and every time you fill up with fuel as that's the only way you can get an accurate average MPG.

Or the easier way, is to just download an app for your phone which does all this for you. I use Road Trip on the iPhone and is excellent at giving you all sorts of running costs for your car. For example, mine tells me that on average 100 miles costs me £14.34 in fuel plus all sorts of other stuff too.

Hope that helps :)
 
I gathered it wasnt quite accuracte but it give me a ball park figure, ill fill up next time and do it properly. Cheers bud!
 
I also have an A3 (140) and have been using Road Trip for over 6 months now. MPG given by the on-board computer is almost spot on.
 
I log all my fuellings at spritmonitor.de, and over the last 12,000 miles what is shown on the DIS is very close to what spritmonitor says - certainly less than 1 mpg different.
 
Ok, so some are spot on.

I spent 600 miles on two journeys 300 up, 300 down. Journey up showed Av 75, journey down showed 82, tank brim to brim bought this out at 67mpg, go figure. and yes I drove like my mum.

Kevin
 
Who cares ? So the dis and app dont agree what are you going to do ? use the car less ?
some things are irrelevant in the short term like MPG, Crunchie says "My S3 only reads 2mpg hi on the DIS which was a surprise." so his car is doing .4 mile to the ltr less than the dis. thats 600mtr. :)
While we are at it, tire pressure gauges are way out, speedo's and fuel gauges too :) as for Sat Navs !!!! follow my RNSE to my post code and you will be in the river !!

These things are a good indication, and like a Dyno they are good for comparisons on the same vehicle but not meant to be gospel .
 
Arnie said:
3.2 and heavy foot ;]
Click to expand...

Unless you sit in a lot of traffic you have a problem mate :) Even fast driving you should get 25mpg but the 3.2 drinks just as much in traffic as it does at 60 mph. I really noticed the difference when i got the S3....rolling the mpg is the same as the 3.2 but stationery the S3 seems to use a 10th of the fuel.
 
paddy said:
Who cares ? So the dis and app dont agree what are you going to do ? use the car less ?
some things are irrelevant in the short term like MPG, Crunchie says "My S3 only reads 2mpg hi on the DIS which was a surprise." so his car is doing .4 mile to the ltr less than the dis. thats 600mtr. :)
While we are at it, tire pressure gauges are way out, speedo's and fuel gauges too :) as for Sat Navs !!!! follow my RNSE to my post code and you will be in the river !!

These things are a good indication, and like a Dyno they are good for comparisons on the same vehicle but not meant to be gospel .
Click to expand...

No-one cares, the point of the thread was to say that there's no point people quoting their DIS readings when talking about fuel consumption as they are most likely out by a varying degree from car to car too by the looks of things.

So the only way to quote a true MPG figure is by using an app or working it out using maths.
 
my 2.0 T is rubbish on fuel tbh most i saw the dis at is 25 mpg full tank about £68 last time 240 miles and i dont drive round like a nutter mayb now and then but thought it was quite shocking tbh but.... it dont me drive it less
 
You have a problem mate, my S3 shows 30mpg most of the time. About 340 a tank.
 
I don't even have the DIS in mine :sob: but I use the site www.fuelly.com/ to record mine, tells you all sorts of averages and keeps track of how much I'm spending too, which I don't like lol

Works on the same principle that the others have mentioned, how many miles covered, how many litres used etc... Apparently I'm averaging 48.4mpg at the moment, the best achieved from a tank being 51.5mpg :)
 
Dec said:
I don't even have the DIS in mine :sob: but I use the site www.fuelly.com/ to record mine, tells you all sorts of averages and keeps track of how much I'm spending too, which I don't like lol

Works on the same principle that the others have mentioned, how many miles covered, how many litres used etc... Apparently I'm averaging 48.4mpg at the moment, the best achieved from a tank being 51.5mpg :)
Click to expand...

That's pretty good.

What kind of driving you doing?

I'm starting to wonder whether something is not running quite right on my car as I do seem to be getting a low(ish) mpg compared to other TDi owners - around 42mpg average
 
Erm most of my driving is dual carriageway/back roads. I get that mpg by poodling to and from work most of the week. I work a funny shift pattern, so I go out on a weekday I usually pop into town and get stuck in traffic etc, so this is a small % of my driving usually, however it seems to have the biggest influence on my MPG dropping (quite obvious really but unavoidable).

I was happy with the 51 but that was purely going to and from work, driving really really cautiously, and it was just generally boring (slow acceleration, slowing down miles before bends etc..) so my MPG has dropped since taking a slightly less MPG conscious approach to driving.

If anyone else is on Fuelly, or wants a look at my MPG stuff, my profile is here: dechill's profile | Fuelly
:)
 
This was my greatest achievement ever. This picture was taken on the 19th of May this year upon reaching Glasgow after my 30 mile commute at 8.30 in the morning. There is no trickery involved, the car had done 30 miles without stopping and as you can see it's on the average mileage for single trip. I've never managed to get anywhere near this figure since.

IMAG0021.jpg
 
1inchpunch said:
This was my greatest achievement ever. This picture was taken on the 19th of May this year upon reaching Glasgow after my 30 mile commute at 8.30 in the morning. There is no trickery involved, the car had done 30 miles without stopping and as you can see it's on the average mileage for single trip. I've never managed to get anywhere near this figure since.

IMAG0021.jpg
Click to expand...

I completely believe this pic - I once hit the magical 70mph average on a single trip back from Ludlow to Shrewsbury. I dont know why, but whenever I drive that route I get insanely high mpg readings.

Its an A-road than you cant really go above 50mph on.

Unfortunately, my normal routine driving is much lower.
 
At a guess, the people who are getting accurate DIS vs brim don't spend much time in traffic, whereas those with inaccurate results spend more time sat still in traffic.

I've found on a couple of cars that when moving it is very accurate, but that it starts to lose its way when sat still... it's to do with how the computer tries to calculate results

To get an MPG figure, divide the distance covered (say 50 miles) by the fuel used (say 1 gallon), gives 50mpg. Alternatively divide the distance covered by the fuel used for a l/100km reading. This is fine when you're on the move. 50miles/1 gallon = 50mpg, or whatever the L/100km reading is.

As soon as you stop, you mess things up. What's 0 miles divided by 1 gallon? What's 1 litre divided by 0km? The computer can't work it out, so either has to bodge a result together by extending the time, trying to calculate a longer average, or just throwing the results away because of a Divide By Zero error.

As an aside, tyre pressures and sizes can make a difference. Running different sized wheels to stock? Running a very different tyre pressure to stock? Expect anomalous results.
 
In my old Mk3 Golf GTI (can't believe a 1995 car had MPG readings but my Audi doesn't..) When I went to Santa Pod to run it, the trip computer said 6MPG after a couple of runs.. and that always sat higher than the actually reading so I wonder what the actual was then :sadlike:
 
paddy said:
Unless you sit in a lot of traffic you have a problem mate :) Even fast driving you should get 25mpg but the 3.2 drinks just as much in traffic as it does at 60 mph. I really noticed the difference when i got the S3....rolling the mpg is the same as the 3.2 but stationery the S3 seems to use a 10th of the fuel.
Click to expand...

I did some motorway driving today, and as it was late at night and bit cold I decided to go easy. re-filled with vpower to full, after doing 90miles at 80mph DIS was still showing 280 more left. so it looks like 370 by DIS, seems about right

but normally I hit 220-230 miles from tank. but I floor the thing every time I have occasion, and when car is 90 degrees warm :) hitting red line very often.

need to pop up to Audi to do software update, and coil pack recall, maybe this will increase mpg a bit
 
Dec said:
In my old Mk3 Golf GTI (can't believe a 1995 car had MPG readings but my Audi doesn't..) When I went to Santa Pod to run it, the trip computer said 6MPG after a couple of runs.. and that always sat higher than the actually reading so I wonder what the actual was then :sadlike:
Click to expand...
the lowest on mine after 30 min hard riding in my 3.2 was 8mpg.... 6 seems very low for TDI
 
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