I'm getting 20-22 mixed driving 23-25 on freeway. With an occasional led foot to get through rush hour.

I'm a 12v'er though. I thought we where supposed to only use Premium Unleaded?

 

So am I still doing something different then? Every fill up I manually calculate the mileage and the two figures agree within 3/10ths of a MPG. If the dash computer tells me I've been making 23.4, my manually calculated value is somewhere between 23.1 and 23.7. That also holds true for the values I said I was getting earlier, my averages are quite consistently about 22.8 city and about 28 highway, even after manual calculations.

Now, by all means, I'm not complaining that I'm getting such good values, but I can't help being curious how seemingly all the other 2.8ers, be them 30v or 12v, are getting such lower figures.

And on a side note, I had my fuel trims read about two weeks ago and they were off by about 8%, indicating a fairly large vacuum leak, and I still get these values for my mileage, so with that in mind and you hinting that a vacuum leak causes lower mileage, I'm definitely curious to how everyone else is doing so much worse.

 

I dunno... EPA puts it at 17-22

http://www.fueleconomy.gov/feg/noframes/12680.shtml

http://fueleconomydb.com/specs/1996/AUDI/A6%2520quattro

 

You tell us? What answer are you looking for here?

As for the OP, that's normal. It's about what I got in my 2.8 and pretty much what everyone else gets. It's a smallish V6, but a super heavy car...we don't sip fuel!

I get about 15 in the S4 .

 

Good point. I posted that while running on a serious lack of sleep, I wasn't thinking too clearly. Looking back at it it's not an answer I'm looking for, I do know what I do to maximize my numbers. I should have posed it as a question for everyone else as to what they're all doing (or not doing) that would make that big of a difference, which putting it that way would require knowing what I do to improve my numbers so everyone else could compare if they are or are not doing something different.

That said, it's pretty known that driving habits have a big impact. As I said, I occasionally have a heavy foot if I need to be somewhere quick, but most of my city driving involves shifting before 2k RPMs, I never go above the speed limit, but if I need to be somewhere quick, I'll accelerate harder to get to the speed limit faster, but don't go above it.
On the freeway, I go the speed limit and if the terrain permits and there is a downward slope, I will ride it in neutral and coast down the slope without going below the speed limit (you said it yourself sineo, we are heavy and all that weight makes for good coasting speeds down a hill) so with that in mind, to the OP: how do your driving habits compare? If you accelerate hard all the time and speed a lot, that will have a pretty large impact on your MPGs.

Other than my granny driving habits, I also have a K&N panel filter which supposedly helps mileage, I always run 91 octane fuel, I have 0w-40 oil in the crankcase (not sure if that makes a huge difference or not but worth a mention), ran seafoam through the whole system and changed the plugs and wires about a month ago, and I recently got a stock muffler setup off a 2002 S4, which I don't expect to be having that large of an impact, but someone once told me that straight through mufflers help mileage so if they weren't full of crap, then that might be helping me a little as well, and if it isn't, well at least it sounds good.

Now, OP: If your driving habits are similar to mine and you're still getting those figures, best I can suggest is a good tuneup (seafoam, plugs, wires, air filter) and replacing the vac lines and see where that gets you.

P.S. Sineo: Diggin the new sig pic. Wish I could find a way to get a bunch of people here in Utah with Audis together to take a pic like that, but I haven't found too many people on here that share residency with me in this state so using the forums to organize something hasn't worked too well.

 

I have no idea how you are getting 28 mpg's on a 2.8L. You would have to be going downhill all the time to get those numbers. You say your fuel trim says 8%? That means its adding fuel because its running lean for some reason. Maybe you have a bad fuel pressure regulator causing a lean running condition, that could be the reason you are getting such good mileage. However thats not good for the motor.

 

Hmm, that seems logical, I'll have to look into it more, thanks for the suggestion.

I'm actually not the one with a VAG-COM, my local tuning shop/mechanic is who told me they were off by about 8%. He also told me that it was only at idle that things went nuts and that everything was normal when throttle was applied. If I remember right, when he showed me the computer showing the 8% difference, there was a - in front of it. I'm not super familiar with the program (or really anything related to the fuel system for that matter) so could that have been a negative 8% and mean something different than running lean? All he told me was that a number skewed that much meant I had a large vac leak somewhere, he never said anything about it potentially being something running lean.

 

A - before the number means the ECM is taking fuel away from the motor. So there is a large vacuum leak somewhere after the MAF sensor. That could also be contributing to your running concern, i would go over all your vacuum lines and check valves when you get a chance.

 

Cool, that makes more sense, thanks for the clarification and suggestions.

I made an attempt to replace the vac lines recently. Got all of the easy to access ones done, but there were two I couldn't quite get to very easily; one that is below the whole vac line harness on the TB, and the other that goes to (I think) one of the mentioned check valves at the front of the engine right below the coilpack harness. I tried unbolting the vac line harness but that didn't get me any closer than I already was, and after getting the easy-to-reach lines done, it was getting dark so I didn't get a chance to try unbolting the coilpack harness to try and get that one. The lines that were running to the combi valves at the back of the engine were either already replaced or came stock as a heavy duty silicone hose, so I didn't replace those.

My guess is that since I replaced those and still had the -8% readings that I either missed something somewhere else or those two that I couldn't get to that I mentioned before are where the entire problem is. Where are some other places to look for a vac leak? And where are all the check valves located and how can I check to see if those are working properly or not?

Lastly, OP: sorry for the threadjack here. Auditech, thanks for the help with this issue.

 

I can't check my mileage cuz my damn lcd broke that shows trip/mileage so I'm paranoid and just watch the needle go down daily. Here is a question, do any of you use injector cleaner? I've used it on previous cars but this car is so touchy I wouldn't wanna F anything up before I do it.