2017 Audi A6 3.0T - REALLY HIGH FUEL CONSUMPTION

[Touareggg]

Hi all,

So I own a 2017 Audi A6 3.0T and I have been quite bothered by the fuel consumption for the past few months or so. Whenever I fill it at the top(93 Premium), it says that I have 730km range (around 450miles) but that is REALLY FAR from the truth unfortunately. This car drinks fuel uncontrollably.
I reset my trip every time I fill up my car to see the actual range and right now I have done almost 350km (218 miles) and it says that I have 150km (93 miles) left, so in total, I realistically have approximately 320 miles instead of 450+. Whenever I drive my car a BIT spiritedly, the range drops by 10km (6 miles) almost every 2 minutes.

Keep in my mind that the fuel where I live is not that cheap and I am trying to save up as much money as I can, but I honestly am really frustrated at this terrible gas mileage.

So my question is this: What can be the reasons for really bad gas mileage? I have done regular oil and filter changes, gasoline system cleaner almost triweekly, tire psi seems to be within specified range.
HOWEVER, I replaced my spark plugs almost a month ago and their gap is 0.028mm (requirement for tuned chips) but It should be 0.032mm for regulars (mine is a regular). Would that gap be the culprit for this fuel madness?

Let me know what you guys think and I will check my car and update constantly.

Thanks.

[pantsoftime]

Have you scanned for codes?

[Touareggg]

Already have scanned, no error codes present.

[pantsoftime]

I think you said you're chipped, I wonder if the tune is hiding some codes. Does it have a stock mode?

[Touareggg]

No no, I am not chipped, however the spark plugs were gapped to chipped settings(0.028mm, while for normal non-chipped cars, the gap should be 0.032mm) and I only replaced those spark plugs. My car is not chipped.

[VinnysS4]

Does your oil have fuel in it? Id suspect injectors spraying too much(or stuck open) if this is the case. If not, then I'd start at the basics.
What does the fuel pressure look like? Any mods?

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[WatchMeSpend]

Put the plugs back to the proper gap, stop running 93 instead of 91, stop putting additives in the fuel. Is there ethanol in the gas as well because if there is find another gas station.

[Touareggg]

91 is not available where I live, highest is 93. Fuel additives have only been put these last 4-5 weeks just to experiment. 10% Ethanol is present in almost every fuel/gas station where I go. I will try to find one with no alcohol concentrate. I will gap the plugs to spec. Thank you!

[Touareggg]

The oil that I use is Leichtlauf High Tech SAE 5W-40 from LiquiMoly. However, I am looking to replace it in the next oil change. As of having fuel in it, I'm not so sure but I have to do some further research about it. Yes, I was suspecting faulty injectors but I have no tools to replace them until mid June.
The fuel pressure is stock, no mods have been done in this car. I just need to make sure I find the faulty part. Thank you!

[WatchMeSpend]

91 is not available where I live, highest is 93. Fuel additives have only been put these last 4-5 weeks just to experiment. 10% Ethanol is present in almost every fuel/gas station where I go. I will try to find one with no alcohol concentrate. I will gap the plugs to spec. Thank you!

Well, if you can't get 91 then....tune it to 93!!

[Touareggg]

I am loving the idea! stage 1 tune soon??

[Valpo A7]

Town driving yeah the fuel economy sucks. 15 - 18 MPG realistically with all the start and stops. Also depends on if you drive in sport or not. Highway driving you should see 28+ MPG.

For spark plugs yeah the gap is 0.032 but it some will still change the gap to 0.028.

Fuel - Audi recommends (does not require) that you run 91 or higher. It will still run perfectly fine on 87 or 89 octane. Running 89 means you make probably 330 HP instead of 333 HP. Not really enough to matter and you will not lose MPG either.


Now for reasons you are down on MPG.

Tire pressure incorrect
Alignment
Dirty air filter
Bad O2 sensors
Spark Plugs
Fuel system problems (dirty injector)
Problems with the cat converters or exhaust system
Wrong motor oil
Driving habits
Excessive idling
Bad gas
Driving in Sport all the time

[Burkeomatic]

Town driving yeah the fuel economy sucks. 15 - 18 MPG realistically with all the start and stops. Also depends on if you drive in sport or not. Highway driving you should see 28+ MPG.

For spark plugs yeah the gap is 0.032 but it some will still change the gap to 0.028.

Fuel - Audi recommends (does not require) that you run 91 or higher. It will still run perfectly fine on 87 or 89 octane. Running 89 means you make probably 330 HP instead of 333 HP. Not really enough to matter and you will not lose MPG either.


Now for reasons you are down on MPG.

Tire pressure incorrect
Alignment
Dirty air filter
Bad O2 sensors
Spark Plugs
Fuel system problems (dirty injector)
Problems with the cat converters or exhaust system
Wrong motor oil
Driving habits
Excessive idling
Bad gas
Driving in Sport all the time

This, I honestly average about 18-20mpg back and forth to work when school is in. I average about 24-25mpg with the cruise set to 100, and I can get over 30mpg under 70mph. It always starts out super optimistic then drops drastically. It is just what cars do.

[WatchMeSpend]

I personally don't drive enough to notice the mpg. If I have the graph showing on the cluster it is for amusement only. Reminds me of the old Grand National boost gauge.

What I can tell you is with a CREC car, so long as you don't drive it in M or S, the clutch on the charger is disengaged until you reach a certain rpm/demand requirement. When I tuned the car to APR Stage 1, and wanted to see what the MPG did, I did see an improvement. At the time I did have the start/stop feature on as well. Driving in D was lacking and I tended to go for Sport, but not too often. Now with a TCU tune, I have way less need for Sport as the transmission is more willing to downshift to help me out. Comfort is asking to die when you are trying to make a traffic light. Auto, plus the trans tune, is the way I drive and only occasionally does the charger come into full play during normal driving.

I later went with the 93 tune knowing that I would have to give up gas with no ethanol but since I was going dual pulley, I wanted all the torque I was able to get. I think that during the colder months, fuel with ethanol gets consumed faster. The car gets noticeably faster in the cold weather, but as traction goes away, there is no point in flooring it unless you like to see dancing TC lights. I don't really notice the MPG. I said to drop to 91 because you wanted to save money and ethanol blends don't go as far on a tank. Here Esso and Shell offer 91 with no ethanol, the competitors have ethanol in every level.

[Alabama]

So I own a 2017 Audi A6 3.0T and I have been quite bothered by the fuel consumption for the past few months or so. Whenever I fill it at the top(93 Premium), it says that I have 730km range (around 450miles) but that is REALLY FAR from the truth unfortunately. This car drinks fuel uncontrollably.
I reset my trip every time I fill up my car to see the actual range and right now I have done almost 350km (218 miles) and it says that I have 150km (93 miles) left, so in total, I realistically have approximately 320 miles instead of 450+. Whenever I drive my car a BIT spiritedly, the range drops by 10km (6 miles) almost every 2 minutes.

I'm confused. Are you concerned with fuel economy or the accuracy of the dashboard "range estimate"? Other AZ threads speak to the lack of accuracy of the range estimate. Apparently it's usually not very accurate and there's nothing that can be done about it, so don't worry. Your post does not actually report what MPG you are getting. Related to type of fuel, most AZ members agree the key recommendation is to use "Top Tier" gasoline.

[Touareggg]

Yes, town driving is horrible. I have reversed the start/stop (vcds) but it barely even helped. Of course, highway mpg is 28+ reaching almost 32 mpg, which is really good. Back in 2016, my friend owned a 2013 Audi A6 3.0T and the range was around 900km+, ALMOST the same as diesel engines and town driving we averaged a good 22+ mpg. However, my case is totally different.
I got the tools to gap the spark plugs and I will do so tomorrow and will give updates.

Tire Pressure - Owners manual recommends for 255/40/R19 tires (non OEM) to run on 36psi front and 33 psi rear but on my drivers B-pillar, for COLD tires it says the PSI that the manual recommends for MAX LOAD and that is quite confusing. On the B pillar it says to run 38 front 41 back for cold tires but checking the table, those psi are for MAX load. Tomorrow I will inflate them to table spec (36 front, 33 rear) and I am sure i will notice a small improvement. My tires right now are Continental ExtremeContact DWS06+ (performance/all season).

Alignment - I am trusting my mechanic on this, however I'll visit Audi Dealership to confirm the alignment is indeed correct.

Air Filter - Air Filter/Housing together with cabin air filter have been replaced and they're brand new.

O2 Sensors - Haven't seen its symptoms as of yet. No engine codes, seemingly fine idle, no misfires, but i do have fuel inefficiency. I might replace them soon.

Dirty Injector - That could be a possibility. Currently, I have no tools to replace the injectors but If I'm left with no choice, I will replace them too.

Cat Converters or Exhaust System - Honestly I never checked these for problems and didn't really see much symptoms either. Will check soon.

Wrong Motor Oil - SAE 5W-40 for these Audis are common, but I will have to look at the manual for that. I'm sure Audi recommends no more than 0.5qt of SAE 5W-40 which is really weird but I am not sure about that.

Driving Habits - I'm mostly on comfort or efficiency, spirited driving only on the weekends rarely.

Bad Gas - I have tried Shell, Mobil, Speedway, Sunoco etc... Which one do you recommend tho?

OH AND ALSO I FORGOT: When I turn my car off and on again after some minutes, the mpg goes completely down low (6-10 mpg) and climbs itself up as I drive. That is very weird.

[Touareggg]

I'm confused. Are you concerned with fuel economy or the accuracy of the dashboard "range estimate"? Other AZ threads speak to the lack of accuracy of the range estimate. Apparently it's usually not very accurate and there's nothing that can be done about it, so don't worry. Your post does not actually report what MPG you are getting. Related to type of fuel, most AZ members agree the key recommendation is to use "Top Tier" gasoline.

I have heard that before (inaccurate range estimate) but honestly I am getting around 15-19 mpg town driving and 26+ highway. Trust me, the range drops quicker than my mood on Sunday nights. I am concerned about fuel economy. It's bad.
Can you elaborate on "Top Tier" gasoline? Is that a gas station?

[Valpo A7]

I have heard that before (inaccurate range estimate) but honestly I am getting around 15-19 mpg town driving and 26+ highway. Trust me, the range drops quicker than my mood on Sunday nights. I am concerned about fuel economy. It's bad.
Can you elaborate on "Top Tier" gasoline? Is that a gas station?

If that is the numbers you are getting than that is about right on what to expect. As for the initial low drop when you start on a new trip those numbers are correct for the dash readout. The dash readout resets each trip and gives you the average for that trip. Low numbers for the first couple miles are normal as you are burning more fuel as you accelerate up to speeds.

You asked what gas station I recommend, I actually don't recommend ANY station. Top tier fuel if you can find it. https://www.toptiergas.com/about-top-tier/ Most decent stations in your area already carry top tier fuel, for my area its actually hard to find gas that is NOT top tier.

[Burkeomatic]

I get my gas at quick trip.

Ethanol concentration can effect your mileage too. If you can find zero Ethanol 93, it may be worth purchasing if the cost isn't too much, do the math.

It is probably easiest to start with the habits though. If you go out and idle through a half gallon of gas on your lunch break or drive where there are lots of stop lights, you won't get good mileage. If you think about it, my A7 has the same curb weight and rolling resistance as my wife's cx9. Everytime you start from a stop, you have to roll 2 tons up to whatever speed you have. When school is out, I average about 24-25 on the way to work. I get about the same back home too.

If you don't like it, hit offer up and grab a $2k prius and drive that on errands. No one cares what you drive anyways.

[AudiInMyA7]

Fuel - Audi recommends (does not require) that you run 91 or higher. It will still run perfectly fine on 87 or 89 octane. Running 89 means you make probably 330 HP instead of 333 HP. Not really enough to matter and you will not lose MPG

So you’re telling me i can put 87 into my car with no problems?

Does this appply to stage 1 93 tunes?


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[WatchMeSpend]

So you’re telling me i can put 87 into my car with no problems?

Does this appply to stage 1 93 tunes?


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The ECU isn't going to make it easy for you to blow it up. It will do what it has to do at the onset of detonation. I wouldn't rely on it and beat the tar out of a tuned car with lower octane in it though. At higher RPMs, mistakes happen much faster and tend to be more devastating. Stock cars at manufacturers spec, have to protect themselves from the non oil changing, wrong gas putting, not fluid checking, general public. German cars seem to get even with you for mistreating them...

[Touareggg]

I don't idle more than 2 minutes most of the time (besides traffic). I am well aware that this car is very heavy however I am certain that I SHOULD be getting more than 450km on a full tank. Efficiency mode helps a tiny bit. Other A6 C7 owners have told me that they can go up to 750km with a full tank, and here I am doing almost half than that with little to no spirited driving and being efficient. I sense something might be off. There is just no way that getting 450km out of a full 20 gallons tank while on Efficiency Mode is normal If I would be getting 620km instead I would never complain about it.

I do have another car which gets me around 45mpg city but I won't have it until October.

I will check my car this weekend to hopefully find anything.

[VinnysS4]

I agree. 450km.. Thats an average of about 13mpg. Should be much higher

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[VinnysS4]

I have heard that before (inaccurate range estimate) but honestly I am getting around 15-19 mpg town driving and 26+ highway. Trust me, the range drops quicker than my mood on Sunday nights. I am concerned about fuel economy. It's bad.
Can you elaborate on "Top Tier" gasoline? Is that a gas station?

So you're getting 15-19 in town and 26+ on the highway and still only getting 450km on 20 gallons of fuel? I'm confused

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[Touareggg]

Yes, you're right. I average around 15-20mpg city and 26+ highway and STILL it all leads up to 450km total range. Either the reading is completely off or something wrong with the car.

[Touareggg]

Yep, exactly. Total actual range I should be getting should at least be mid-high 600's and possibly low 700's. Instead I get half of that.

[Valpo A7]

If you are stock then you can run 87 if you wanted, it will just be down on some power. If you are tuned then you probably need to run the 91 or 93 octane. Mine is stock and I have been feeding it 89 octane for the last 87,000 miles. Don’t know what the original owner fed it.

[VinnysS4]

Yes, you're right. I average around 15-20mpg city and 26+ highway and STILL it all leads up to 450km total range. Either the reading is completely off or something wrong with the car.

Are those mpg numbers you calculated from the km driven vs gallons used or is that the mpg read out on the dash?

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[Burkeomatic]

What I would do is go old school instead of relying on your computer.

Fill the car up (don't top it off) and set the trip gauge to zero. Drive if around for a couple of days, fill it up at the same place and same pump if possible, and see how many gallons it took. Do the quick math and you will have your answer.

[AudiInMyA7]

Yeah hate to break it tonyou the DTE is a straight lie.

My fill up says about 450 miles and i get maybe 320 MAYBE i dont think its ever been spot on


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[Touareggg]

I tend to run 89 at times but mostly 93. For now, main concern is resolving the fuel efficiency, after that, I can use 89. I am just trying to get more out of a full tank. 450km is VERY low.

[Touareggg]

Yep, I do exactly those. I even calculated km's on paper and did the math and I still get around 400-450km (full tank ~ 20gal.) (same as dash reading).

[Touareggg]

Those numbers are from dash readout, which is the same with calculated on paper even, and trip meter (I reset it after every fill)

[Touareggg]

At least you're getting 30-40 miles more than me lol. Keep in mind that I don't do much spirited driving with it, it's kept at comfort or efficiency modes all the time. I get 300 miles range. My friend has an sq5 and he floors it almost all the time and he gets around 440 miles. Something feels wrong I'm sure of it.

[Alabama]

Yep, exactly. Total actual range I should be getting should at least be mid-high 600's and possibly low 700's. Instead I get half of that.

I suspect the problem is more likely a math problem than a car problem. Sometimes you are using "miles", sometimes "kilometers". If I put 20 gallons into the tank, get 25 MPG when highway driving, and drive until the tank is empty, my odometer range will be 500 miles (25 MPG times 20 gallons). As Valpo A7 wrote, the MPG you report are about average for many AZ members. The system that reports a "range estimate" on the dash as mentioned above is not very accurate and there is no way to correct that. If you are concerned about efficiency, test it the way Burkeomatic recommends (using the odometer and the gas pump).

[Touareggg]

I have tested it many ways. Also, I grew up in Europe and I recently moved to the U.S and I only used metric system that's why I mention both miles and km. My main concern is not about inaccurate dash readings but the actual total range that I get. It fluctuates a lot and knowing how easy I drive, 450km (280 miles) just isn't enough. I'm almost 280km (175 miles) short based on some calculations and not only on the dash readout, I should be getting around 700km (440 miles) considering that my mpg shows 25+mpg even during mixed (city & hwy) rides. The mpg and range readings can be both inaccurate. All I am trying to say is that I simply refuse to believe my max range full tank is 450km. I have had many V6 petrol audi cars and they have much better mpg (and range) (some could even reach up to 800km).

I will do some touchups to hopefully get it a bit higher.

A bit of Math:
- A few months ago, I was moving from Boston to Connecticut and back almost three-times a week and after I topped my tank and went on the highways, the mpg would even reach 31 (and stay like that the whole ride) and I would STILL get less than 450km. (car was at 55 miles on acc). 31mpg * 20 gal = 620 miles, lets reduce a good 30 miles maybe from city driving, 620 - 30 = 590 miles. Now tell me why I was still getting 280 miles range?

I have every reason to believe that it's chugging more fuel than it should.

[Alabama]

A bit of Math:
- A few months ago, I was moving from Boston to Connecticut and back almost three-times a week and after I topped my tank and went on the highways, the mpg would even reach 31 (and stay like that the whole ride) and I would STILL get less than 450km. (car was at 55 miles on acc). 31mpg * 20 gal = 620 miles, lets reduce a good 30 miles maybe from city driving, 620 - 30 = 590 miles. Now tell me why I was still getting 280 miles range?

As best I can tell, you are still using the built-in computer to calculate your MPG. As several AZ members have posted, the built-in computer is not accurate on anyone's car. You need to do what Burkeomatic in post #29 recommended. If you are really only getting 280 miles on 18 gallons, then your true MPG is about 15.5 MPG (not 31), which seems low for highway driving. Report that number and the knowledgeable folk here may then be able to make better suggestions. Note that AZ member AudiInMyA7 in post #30 only gets about 320 odometer miles on a tank of gas, not too much different from you.

[A665]

The dash reading is not reliable. Particularly if your math indicates a certain average mpg that conflicts with what your dash displays, it’s pointless to be worried about the dash reading.

[Valpo A7]

The dash reading isn’t right BUT if the dash readout is low then the actual will be low as well. Yesterday I drove 2 hours to my parents. Going there I was a bit spirited in my style a couple times getting on it to pass and going there the dash read about 25 mpg. Coming home I drove it easy and not spirited and the dash reading was about 29 mpg. Both times I looked at the on board computer readings and the instant fuel economy was over 30 while cruising at 80 mph on flat ground with the cruise set.

[Alabama]

The dash reading isn’t right BUT if the dash readout is low then the actual will be low as well. Yesterday I drove 2 hours to my parents. Going there I was a bit spirited in my style a couple times getting on it to pass and going there the dash read about 25 mpg. Coming home I drove it easy and not spirited and the dash reading was about 29 mpg. Both times I looked at the on board computer readings and the instant fuel economy was over 30 while cruising at 80 mph on flat ground with the cruise set.

In a different AZ thread "S6 real world MPG?" gk1 in post #5 reported about 17 MPG for an S6. If the car has about 18 gallons usable, then the true range will be about 310 miles. However, in post #13, Valpo A7 referenced the website "fuelly.com", which does give a higher MPG for an A6, about 21 MPG across model years. That number should yield a true range of about 380 miles. Maybe OP will report a number based on Burkeomatic's suggestion in post #29 here.