MPG not adding up

[GibbyNI]

Ok so I have had my 1.0 Tech for just over 6 months and 6.5k miles and something just isn’t rite with the mpg. I have logged every penny of petrol and mile done and the car always overstates the mpg that it’s giving by about 3 or 4 mpg. I always re-fuel as soon as the light comes on and fill the tank. Every time I check the since re-fule mpg and is higher than my calculations. Even the long term value is higher.  I know over the 6.5k I have received 38.5 mpg, the car has never told me anything below 40 mpg. 

 

Anyone else noticed this ?

[Gomezz]

I find it just the same with my 2ltr TDi  4x4 DSG, it was also the same with the last Octy 2ltr Tdi I had, around 3 to 4 mpg optimistic .

[dave_knight]

Yeap, my 1.6 TDI DSG seems to return 5-7mpg less than the computer is telling me.  I also monitor the true mpg calculated from fuel used over distance travelled based on receipts and a calculator!  I have just put this down to over optimistic software not being able to calculate the mpg correctly or some weird software algorithm that seem to ignore part of the journey.  Also remember that the mpg quote in the brochure is completely over optimistic and seldom represents real world driving.

[Ootohere]

^^^ The Official figures from EU testing were never for a vehicle on a road driving with people and luggage in it, it was EU testing in Temperature Controlled buildings.

Hence discontinued. 

Even the WLTP is not a car with the seats occupied.

 

As to the accuracy of the computer, the cars have different brands and size of tyres and people have more or less air in them.

They can not be accurate unless you calibrate them individually. but as they are they are just as they are set at the factory which will be all the same.

 

Your Speedo is not accurate and best check the odometer accuracy comparing against GPS / tracker app. That can be a bit out as well.

 

Edited 2 January, 2019 by Skoffski

[Luckypants]

It is well known that the mpg figures from the computer on most VAG cars are optimistic. Google will show up the same complaint from Audi/VW/SEAT drivers also. The calculation are based on a certain wheel/tyre size and if your car differs it can throw the calculation out. It can be fixed via VCDS / OBDeleven to change the 'weighting factor' given to the mpg calculations. I had mine done on my previous Leon 16.TDi and on my current Karoq. The bonus of correcting it is you get a more accurate range figure also. FYI my 2.0TDi needed a 4% correction.