Re: Poor Fuel Efficiency
 

Thanks Tomashek. I noticed those hwy#s too. In spite of my rather dismal city numbers, highway has been surprisingly good: 7.5 - 8.5 with heavy inclines (#99 to Whistler). Why this break-in period results in bad city & good highway #s I am not technically-inclined enough to know, but it is promising.

Re: Poor Fuel Efficiency
 

Actually, i just check today.
Mine was 11.5L/100km
(I have no idea how it came down to this low or how i saw 15)

Re: Poor Fuel Efficiency
 

I get the same discrepancy between the computer's L/km vs. calculating fill-up/km reading. (computer reads around 11 and I calculate around 15)

Does the computer know what tire radius I have? i.e. is there a set-up I can do? or is it dealership and/or VAG-com?

Thanks.

Re: Poor Fuel Efficiency
 

I don't know how to reset the computer for a different tire radius. However, both my winter and the OEM all-season tires have an identical circumference, so the trip computer should be accurate.

I am over 9400 km now, with the trip computer reporting an optimistic average of 10.67 L/100km, whereas the actual consumption has been 11.6 L/100 km (1100.71 litres to drive 9477 km).

I would appreciate if others would indicate it in their posts whether they are reporting actual (fuel purchased/distance travelled) or indicated (trip computer) fuel consumption. This way we can compare real world results, and not "apples to oranges."

Re: Poor Fuel Efficiency
 

Just a thought about the accuracy of calculating fuel economy from fill up to fill up. There is a margin for error to the actual fuel you get from the pump. I am pretty sure they over charge for the amount of fuel you actually get in the tank. There's no way to prove it, unless you take a measuring cup with u to fillup.

That being said, my trip computer says 11.3 but I calculate 12.0 over 1500 kms

Re: Poor Fuel Efficiency
 

Just to add to something.
If you're using the onboard computer to calculate the efficiency.
It can be very misleading (happened to me).
You have to drive a bit to see the more accurate ones.

Re: Poor Fuel Efficiency
 

Wow, 7.5L/100KM is great for a vehicle like the Q5 - now I want to get the wife one even more! At what kind of speeds are you able to achieve that economy, and how are you collecting your data?



Yup, that's why only with many fill-ups (think of them as trials in a science experiment) does the figure become statistically significant. It's rather easy to fill up to different levels every time, or even have a pump shut off early/late compared to other pumps, making single-tank data nearly useless.

Re: Poor Fuel Efficiency
 

Exactly - that why I am reporting data after nearly 10,000 km and many fill-ups. Sure, on any give fill-up I may have added one litre more or one less that the previous time, but after so many fill-ups, the error becomes very small. This is because one can simply take the total km travelled and relate that to the total fuel purchased.

Regarding the measurement of fuel at the pumps, there is a tolerance for the error, and it could result in one getting slightly more or slightly less fuel than indicated. The calibration for the pumps is inspected regularly. I am sure that there are some stations that try to shortchange the customers, but overall I believe that most employ accurate pumps.

Does anyone have evidence of the trip computer agreeing with the pump data over a significant number of fill-ups? It seems to me that the difference is due to an error in the calibration of the trip computer.

Re: Poor Fuel Efficiency
 

"Wow, 7.5L/100KM is great for a vehicle like the Q5 - now I want to get the wife one even more! At what kind of speeds are you able to achieve that economy, and how are you collecting your data?"


I usually do 117, and simply switch trip computer to real time fuel consumption.

14,000 km update on fuel consumption
 

Over 14,000 km now with my Q5 2.0T, and the indicated fuel consumption is averaging at 10.8 L/100km. However, the actual fuel consumption is averaging at 11.8 L/100km. The trip computer has been consistently underestimating the fuel consumption by 1.0 L/100 km since I got the Q5 in February.

To those posting incredible fuel numbers - have the courtesy to let us know whether they are the optimistic (bogus?) trip computer data.

http://www.fuelly.com/sig-metric/63373.png