So I have an 2006 A6 with 72k miles on it. I put 91 octance fuel in my car and keep up with all maintenance since it's kinda covered under my extended service maintenance plan.

Lately i have noticed that mileage has been dropped a lot. I use to get 20mpg in the city but now i hardly get 13. So the Audi tech put this fuel cleaner can in my car and I did it again after 2 weeks but that really didnt help much. He's telling me that whole intake has to be cleaned but I am not sure if I should invest in it because it cost like $600 and no guarantees that it'll increase the mileage.

Does anyone have any suggestions on what I should do here? I think 13 is pretty low and its really hurting me at the pump. Thanks in advance...

 

So no one has any ideas on what's going on and what can be done to increase the mileage? I have fairly new tires and tire pressure is ok. Service was done a month ago and that didnt help either. No other issue with the car and its running perfectly fine except the lower gas mileage

 

There are so many possibilities. If you really want to be sure, start scanning for codes with a vag-com. There might be some components affecting your gas mileage but they don't throw a check engine light (yet).
Some examples that could affect gas mileage: MAF, O2s, Airfilter, hoses, coil packs, spark plugs, basically all the stuff in the engine room. Most will throw a check engine light sooner or later when they completely fail. However until they reach a certain threshold they will only be logged internally and cannot be read with a generic obd2 reader.

You could start shooting in the dark and do the basic tuneup for starters (replace spark plugs, coil packs, new air and fuel filter, maf cleaner, carbon clean up). Depending on how long ago your last oil change was you could also do that with a lower viscosity oil (but make it still is within the approved list for your Audi).

 

All the services are upto date and the audi tech...who also does small jobs on the side, hooked it upto computer and didnt find any codes plus the 70k service was just done like a month ago. Spark plugs are fine and so is air and fuel filter. I can check on carbon cleanup but audi is performing all services without any issue.

 

Unless you manually calculate gas mileage (mpg), it's difficult to really know how your car is performing. Are you sure your style of driving and duration of trips has not changed? More, shorter trips will reduce mpg. Sitting in traffic more frequently will reduce mpg. The other big factors are tires, tire pressure (which you claim is good), air filter, spark plugs, and finally the type of gas used. Sometimes summer blends have more ethanol which reduces mpg, in my experience. Rather than pay $600 to the dealer, you can dump a bottle of fuel injector cleaner into the gas tank.

 

Nop...driving habbits havent changed and same kind of 91 fuel. Tried fuel injector cleaner cans...my audi tech gave me an extra can to use it too. Nothing is helping really and from 20 to 13 kinda sucks...and i was doing 20 with city driving stop and go and 26 on hwy.

 

Well first of all your Audi tech might not be so good as you think. I have had a lot of bad experience with some of those techs. Even if he is telling you that your spark plugs are fine and the coil packs are good, you are still within the range where Audi had a lot of problems with the coil packs (I think up to 2008).
If you never had spark plugs changed or Coil packs I personally would go ahead and replace them all. The decision is still yours of course.

 

Did you ever resolve the low mileage issue on your A6? For my A4, 02 and 05 A6, there were coil recalls from Audi. Even though the coil packs didn't throw a check engine light, it did affect my mileage on all 3 cars.

 

just a thought. did you check the pvc. could be gunked. check all pvc lines

 

I am going through the same issue with my 2005 A6, 4.2L V8 /98.6K on the dial. I expected to have poor fuel Economy because I am deal with a V8. I was getting 11 mpg when I bought it, but have dipped as low as 8.5 recently. I recently changed my engine Air filter, which was extremely dirty (may not have been changed since new. My fuel economy is starting to inch up, but I have not filled it up since replacing the filter. I suggest you check your engine air filter and change it to be safe.