New-to-me '13 S6....getting terrible fuel mileage

[LawDawg]

So I just picked up a '13 S6 after trading in my '11 S4. On paper, the S6 only pays a 1 mpg penalty for the 2 turbos, 2 extra cylinders, extra displacement, and extra weight. S4 is billed at 18 city / 28 hwy; the S6 at 17 city / 27 hwy. Real world, I was getting an average of 20 mpg over a tank of gas, so I was expecting 18-19 in the S6 based on Audi's economy figures.

I'm getting 14 mpg in the S6! I know what you're going to say: "stop smashing the gas around town in your fun new car." But I'm NOT. With all the oil screens/turbos/motor mount issues out there, I bought a 4 yr. aftermarket warranty. The waiting period is 30 days and 1000 miles (to make sure you're not paying $4.5k for a warranty to cover an existing $12k problem). So as a consequence, I'm driving like there is an egg under the gas pedal. I can't imagine what it would be if I really was playing with my new toy.

Is this what I should expect, or does it sound like something is amiss? The only code that I'm seeing for the engine is:

17881 - Exhaust Pressure Control Valve - Signal Too Low

Is there any chance that this is the cause? I have no other relevant codes, and no engine light. I was really expecting to have a real-world combined of 18-19 mpg, and am not very happy with Audi if the S6 is really this inefficient.

Hopefully there is something that needs to be fixed (inexpensively, while I'm wishing), because the car is AMAZING otherwise.

[gk1]

Sadly I've seen similar back in the day with a 2.0T. Turbo does not necessarily equal better fuel economy. As soon as boost comes in mpg drops like a rock...and boost is damn near always coming on no matter how light you are on the pedal.

I came from a 2012 S4 averaging 19.7 mpg @ 46 MPH. Now in the S6 when driving similar MPH I manage 18.7 mpg. (Spot on at -1 mpg) But after moving and changing to a lot more city style driving I now get only 15.7 mpg @ 26 MPH. But I do have a heavy foot.
Also FWIW I have re-calibrated the DIS to more accurately reflect the roughly 8% over-estimate built in from the factory so if you are showing 14mpg on the DIS it is more like 12-13 mpg. Do you do all city driving? Was the car exceptionally well maintained prior to your purchase?

I don't see that particular code number as something available as a DTC. Using the text I see "P047700 Exhaust Pressure Control Valve "A" Low" maybe that is the same as what you see but zero details on it.
A quick online search indicates it "could" cause performance issues. "...there may be some detectable symptoms. These include reduced engine performance, insufficient turbocharger pressure, and the illumination of the Check Engine Light. " At any rate the sensor or wiring should be fixed.
Shouldn't the dealer's limited sale warranty cover you or are you saying they offered no such warranty and you have to wait for your aftermarket warranty to kick in?

[Valpo A7]

Your MPG is low but at the same time very few on fuelly.com are seeing the 27 highway that Audi is claiming for a 2013 S6

http://www.fuelly.com/car/audi/s6/2013

[MVR 155]

I also came from an S4 (2013). I would get around 19mpg's with mostly "in town" type driving. My S6 gets about 3mpg less and I don't think 25-27mpg's on the highway is much of a reality. It's a heavy car with a decent amount of HP which equates to a gas pig. I have a good friend who also went from a 2016 S4 into a 2018 S6 and he made the same comment that it's much thirstier.

[gk1]

Sadly the best I've been able to do on a road trip was 21-22. Mind you this is over a full tank. I can manage 23 on an all flat highway trip but a real 27 (29-30 on stock DIS) for any extended period of time is a dream. Even if you had a combination of of ideal conditions...temperature, flat 50 MPH highway, 4-cylinder mode always activate with highly pressurized fuel efficient narrow tires it would be hard to even sustain 25 mpg.

[wwhan]

On a flat highway (no hills) on cruise control at 72mph, I get around 27-28 mpg, but on a freeway with hills it drops to about 25mpg (this is with throttle & transmmsion in auto, not dynamic mode).

Around town, I typically get about 11-12mpg, but have attained 16mpg in town by driving very gently.

The S6 has a lot of mass and it takes a lot of energy to accelerate even moderately.

[LawDawg]

Around town, I typically get about 11-12mpg, but have attained 16mpg in town by driving very gently.

Sounds like I'm not alone. I wonder who at the EPA got paid by Audi to certify the 17 city mpg figure?! I LOVE my car, but these figures are freakin' terrible. Makes me feel kinda guilty for not looking harder for a TDI. Yes, I'm aware of the irony.

Since I'm going to be lighting my money on fire at the pump anyway, I might as well start stomping on it.

[cval3]

Same boat. Got my '13 S6 in August of '18. I zero'd out the long-term trip odo Day 1 and over the course of the year I was averaging 14.5mpg. Combine that with a complete failure of the oil separator, thankfully covered under my extended warranty after the $250 deductible, and I am 'out' on this car. Couldn't justify in the long term. Ended up getting a '16 A7 TDI, now seeing consistent mpg's in the high 20's low 30's, and for me, couldn't be happier. Helluva car and it was a blast but I was too nervous of the long-term costs of repairs with motor mounts, air suspensions, and all the electronics, to actually ever push the car to the limit.

I also came out of a '13 S4 but needed more space because of our 1yr old.

[LawDawg]

Same boat. Got my '13 S6 in August of '18. I zero'd out the long-term trip odo Day 1 and over the course of the year I was averaging 14.5mpg. Combine that with a complete failure of the oil separator, thankfully covered under my extended warranty after the $250 deductible, and I am 'out' on this car. Couldn't justify in the long term. Ended up getting a '16 A7 TDI, now seeing consistent mpg's in the high 20's low 30's, and for me, couldn't be happier. Helluva car and it was a blast but I was too nervous of the long-term costs of repairs with motor mounts, air suspensions, and all the electronics, to actually ever push the car to the limit.

I also came out of a '13 S4 but needed more space because of our 1yr old.

We are in VERY similar circumstances. Thanks for your info!

[viceroy1976]

I too came from a S4, but a 2010 manual, and then a 2013 A5 3.0T into the S6, and my experience has been that in the first month or so of the S6, my fuel consumption was worse than the previous two cars, getting just less than 15mpg, but I've gotten the consumption down to around advertised figures (I mainly do city driving) and my last tank averaged very close to the advertised 17mpg. I can easily see the car getting 27mpg on the open road.

[dab]

So I just picked up a '13 S6 after trading in my '11 S4. On paper, the S6 only pays a 1 mpg penalty for the 2 turbos, 2 extra cylinders, extra displacement, and extra weight. S4 is billed at 18 city / 28 hwy; the S6 at 17 city / 27 hwy. Real world, I was getting an average of 20 mpg over a tank of gas, so I was expecting 18-19 in the S6 based on Audi's economy figures.

I'm getting 14 mpg in the S6! I know what you're going to say: "stop smashing the gas around town in your fun new car." But I'm NOT. With all the oil screens/turbos/motor mount issues out there, I bought a 4 yr. aftermarket warranty. The waiting period is 30 days and 1000 miles (to make sure you're not paying $4.5k for a warranty to cover an existing $12k problem). So as a consequence, I'm driving like there is an egg under the gas pedal. I can't imagine what it would be if I really was playing with my new toy.

Is this what I should expect, or does it sound like something is amiss? The only code that I'm seeing for the engine is:

17881 - Exhaust Pressure Control Valve - Signal Too Low

Is there any chance that this is the cause? I have no other relevant codes, and no engine light. I was really expecting to have a real-world combined of 18-19 mpg, and am not very happy with Audi if the S6 is really this inefficient.

Hopefully there is something that needs to be fixed (inexpensively, while I'm wishing), because the car is AMAZING otherwise.

you usually don't buy a 420 hp car for the gas mileage. Surprising the apr tune helps the engine breath as my s7 averaged 24 on the highway with the cruise on 90mph and my rs7 is very close at 23mpg again cruise set at 90mph.

[LawDawg]

you usually don't buy a 420 hp car for the gas mileage. Surprising the apr tune helps the engine breath as my s7 averaged 24 on the highway with the cruise on 90mph and my rs7 is very close at 23mpg again cruise set at 90mph.

I know, I know. I'm not griping because I thought I was buying a Civic hybrid. I'm just annoyed that the published EPA figures are so far off. I was ok when I went from my A4 to my S4 and lost a few MPG, but it was in keeping with the economy numbers from Audi. Part of my calculus in buying this car was whether I held out for a TDI. I let a perfect one slip away because I didn't have a buyer lined up for my S4 at the time. I was looking for monster torque and the economy. Well, this S6 was local, LOADED, and the price was right. At that point, given that everything was lining up perfectly, I decided I was willing to suffer another small efficiency hit.

My only complaint is that the hit was larger than the billing. Kinda thought it might be an indication that something was amiss in a sensor or somewhere else in the engine/emissions. I LOVE this car, and I'll deal with it...if I must. Haha. Maybe a TDI will be in my future after a few years.

[IowaRS7]

I would certainly look into the code issue, maybe there is an issue with the valves or the CATs. Have you checked the air filter condition? When were the plugs last checked or replaced? I usually replace plugs on turbo cars every 25-30K.

[daytona rs7]

for more comparison, i get sub 10mpg in heavy traffic. 15 around town. 20mpg mix. 25-27mpg all highway.

[LawDawg]

I would certainly look into the code issue, maybe there is an issue with the valves or the CATs. Have you checked the air filter condition? When were the plugs last checked or replaced? I usually replace plugs on turbo cars every 25-30K.

The car is due for a DSG service in not too long, so I'll have the stealership poke around and see what the issue is. If it's not super involved, I'll just do it myself. I can't say about the plugs, but the prior owner was very meticulous about the scheduled maintenance, and the car has 79,000 mi. on it. I assume that the plugs were changed at the last interval recommended by Audi. Not sure about the air filter, but I already have a replacement on the way, and I see that the release tab on the airbox has been broken, so I know someone changed it at one point at least.

for more comparison, i get sub 10mpg in heavy traffic. 15 around town. 20mpg mix. 25-27mpg all highway.

I have a feeling that this is what I'm seeing. I just don't have a large enough sample size yet.

[Mathews]

2013 S6 - I get 8-10 in heavy traffic, 11-14 driving around town and 22-24 on highway.

[OaborbaG]

If I do mostly city driving, my mpg is usually below 15, typically I see about 14.1 or so. it's not until I do a lot of highway miles, like 20+ miles that the short term trip gets over 24. If I stay below 75mph I can get close to 30. Did a 70 mile trip last Saturday with cruise set at 72.5 and I got 31.4 mpg.

The cars are heavy, so decent city mileage is hard to come by. I think what you're getting is normal, sadly.

[gk1]

...and it's just another reason why the C8 is a 2.9T now....
or
...if you are ROW...
diesel

[gk1]

Also did anyone else notice the EPA website dropped the C7 S6 from 17(18)/27 before 2018 to a more realistic 16/24 in 2018...and that's with stop/start and any minor advancements that may have taken place over 5 years.
https://www.fueleconomy.gov/feg/Find...37769&id=39393

[Lilrckt]

to add to the mix. On my 2013 I have noticed the DIS is about 2mpg optimistic.
So real data on my commute 20 miles with 25% freeway 50% 40mph hilly backroads and 25% in city, I'll average about 18, I did get 20 once but that was in efficiency mode and really trying to baby it.
Full city driving is about 10ish
60mph flat freeway cruise control was 28mpg, 80mph flat cruise was 23mpg.
However all the figures are about 1-2mpg better than the 2016 BMW 550xi that I had before

[flyfishing]

I've just accepted (for a while now) that all cars I have will get 14-16 mpg city on premium. Just accept it and life is better. I have't had a car in prob the past 7 years or more that got better than that.

[PSUGOLD]

I got my 2016 S6 a couple months ago, mostly drive around town, averaging around 15-16mpg. D mode most of the time, some S mode. On the highway, i was getting around 23-24 per trip, little lower than expected and less than the 27-28 I got in my S4, but not horrible I guess.

[ryanlada]

2016 S6...

I managed 36.9 on the DIS in efficiency mode with cruise set at 62mph. Mostly flat.

On a separate trip, 263 miles averaged 30.5 on the DIS @ 80mph using cruise from northern Chicago burbs to U.P. Michigan efficiency mode.

Stage 3 seems to have helped the mpgs...

Prior to stage 3 i would get about 27mpg on the same trip to the U.P.

Edit: Start-Stop disabled.

[bknewtype]

all HIGHWAY i can get around 26pmg in D mode
all HIGHWAY i can get around 23 in S mode
only CITY i get around 9 mpg in d mode
mixed HIGHWAY and CITY i get around 16mpg in D mode

adding the jb4..lulzzzzz. but smiles per gallon :)

[Hofahome]

I never look at my gas mileage but here it is. I am stock on 2018 S6. Mainly DD commute in suburbia with good mix of stoplights and a few backroads that I go WOT nearly everyday. I have the auto stop/start disabled - not a fan of it.
Btw, in playing around I have found that using adaptive cruise control can get you a little better mpg.


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[flyfishing]

my prob is even if i drive conservatively, on certain roads with no or low traffic, i floor it for fun and bye bye gas mileage

[AgisS4]

Also did anyone else notice the EPA website dropped the C7 S6 from 17(18)/27 before 2018 to a more realistic 16/24 in 2018...and that's with stop/start and any minor advancements that may have taken place over 5 years.
https://www.fueleconomy.gov/feg/Find...37769&id=39393

How could you have such a discrepancy with same powertrain?
I am thinking of buying a2017 S6 P+

[LawDawg]

I never look at my gas mileage but here it is. I am stock on 2018 S6. Mainly DD commute in suburbia with good mix of stoplights and a few backroads that I go WOT nearly everyday. I have the auto stop/start disabled - not a fan of it.
Btw, in playing around I have found that using adaptive cruise control can get you a little better mpg.


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Holy shit! 19+ mpg over 700+ mi.?! That seems really good.

How could you have such a discrepancy with same powertrain?
I am thinking of buying a2017 S6 P+

My gut tells me that Audi was overly optimistic initially.

[gk1]

Holy shit! 19+ mpg over 700+ mi.?! That seems really good.

That pic is from DIS which is generally 8% optimistic unless modified, so more realistically 17.7mpg. which is in line with my own 17.1mpg average over 36000 miles.

My gut tells me that Audi was overly optimistic initially.

Sadly Audi has nothing to do with it the EPA/government tests and sets those numbers...no explanation why it dropped so much in the final year.

[Hofahome]

That pic is from DIS which is generally 8% optimistic unless modified, so more realistically 17.7mpg. which is in line with my own 17.1mpg average over 36000mi.

How can I modify? Use my vagcom?
I love how when you fill up it says like 8000mi to empty and you are at the pump 3 days later. I swear the audi programmers had a laugh on that one.


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[digdah]

I am averaging 19 to 20 mpg combined with a decent mix of highway and back roads. I go to work on the highway then home on the back roads. I get similar average mileage with the other car in our stable which is a 3.6r Subaru Outback but there is absolutely no comparison when it comes to smiles p/gallon. None! On the surface streets I get ~ 17-18 mpg and on the highway I see a wide range from 20-26 mpg depending on if I have a clear road ahead of me or not. I get on it each and every fkn time I can cause it is too much fun so I am in no ways trying. Going stage 2 seems to have improved my total mileage as well. I used to barely get 250 miles a tank now I'm getting 300 miles from the last 2 fillups. I believe my averages will also go up so no complaints from me on a v8TT tuned to almost 600HP.

[gk1]

How can I modify? Use my vagcom?
I love how when you fill up it says like 8000mi to empty and you are at the pump 3 days later. I swear the audi programmers had a laugh on that one.


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Yep VCDS
I think...
[17-Instruments]
[Coding - 07] > [Adaptation - 10]
Scroll down in the drop down list until you see something like "fuel consumption adaptation" - change the value from 100 to 108 (8% difference):
test, save whatever.

[vman932]

Here is a data point, or two....

I have recorded all my fillups for the 10,000+ miles I have put on my 2013 S6. My lowest mpg for a full tank was 14.3. This was mostly very aggressive driving in the mountains. If you throw out that data point, the next lowest is 17.6. The highest is 27.4. Most of my driving is suburban. The few times I have done a full tank on the highway, they have been 25~26+ mpg and that's at 80+ mph and not being afraid to pass . These mpg values are hand calculated based on miles driven/gallons pumped. I have also checked my odometer against both gps and interstate mile markers (over 40+ miles) and have taken odometer error (2.5%) into account as well. My overall mpg for the ~10k miles is 20.4 (actual calculated) compared to 21.2 on the dash. So my dash display seems to be ~4% optimistic over the those 10k miles. I also check the calculated vs dash mpg on each fill up and it is typically 3%~5%. There are a few outliers, but not all pumps shut off at the same point and I usually top it off up to the next whole dollar. I explain all that to let you know I track all my data and have a good idea of how my dash compares to actual. That said, I have seen extended periods of 30+ mpg when taking it easy on the highway. See image below showing 30.2 mpg for 88.7 miles with an average speed of 70 mph. Most of this was with the cruise on 75 and slowing for traffic at times. AC was definitely on as the dash was showing 96* :) Earlier in the trip, I saw as high as 30.8 mpg over 27.9 miles. Full fuel log also below. Of note: APR stage 2 ECU/TCU and APR downpipes at 48,500. SRM RS7 turbos, APR Stage 3 ECU, and APR exhaust at 54,800 miles.

Capture 30.2.JPG

Capture 30.8.JPG

Capture excel.jpg

[ryanlada]

Every turbo car i have ever had got better light load/highway mileage once i upgraded the turbo or exhaust. Same has held true on my S6. RS7 turbos and APR downpipes significantly improved my cruising MPG. I don't have as detailed records and I'm relying on the optimistic dash mpg meter but i routinely see high 20's on daily drives, and the most extreme was a roughly 100mile cruise with speeds locked at 60mph which netted a 36.9 average on the cars dash mpg meter.
Even taking out 20% for optimism leaves an impressive mpg number for a roughly 600hp heavy cruiser.

[MVR 155]

I’ve noticed that both my previous S4 and current S6 were quite optimistic on the DIC with average MPG and range to empty. Typically the MPG was/is at least 1-2mpg over what the actual is and the range is “tripping on mushrooms” nuts!!!! My Yukon Denali is about 0.5-1.0 optimistic on mpg’s and is much more realistic on range. Surprisingly..... my C5 Z06 is the most accurate of them all, it’s within 1-2 tenths of mpg’s and pretty close on range. The most ridiculous thing is that it’s actually the most fuel efficient car I own!!! It easily gets 17-18 in town and getting 27-29mpg’s on the highway is no problem. Being light and slippery has it’s benefits!!!

[MOHCTP]

2018 S6
Last 10-15 fill yps I avarage high 10 low 11 mpg and i calculate it myself miles drivven per amount of gallons , i was away for 2 weeks wife drive the car I filled up and she avaraged mid 13 mpg , drive 90% city pretty agressive

[wwhan]

EPA Requires Audi, Bentley, Porsche and Volkswagen to Correct Fuel Economy Labels for a Number of 2013-2017 Gasoline Powered Vehicles 08/30/2019

But, this looks like it mainly affects, A8L, RS7 & S8 for 2013-2016 Audi & not by much: https://www.epa.gov/recalls/fuel-economy-label-updates

[ItsLarryG]

I see my HUD that says 23MPG, but when I have to fill up after 300ish miles, I know I’m getting around 15. Whatevs... I didn’t buy a turbo V8 for the gas mileage.