tdm1995

Just picked up a 2016 A6 2.0T Premium Plus. Loving the car, but the MPG reported in long-term memory is freaking me out. Won't be sure until I finish my MPG test on my first full tank of gas,,, but the problem looks to me to be -- the MPG calculator update triggers on a timer pop at low speeds (or when parked and idling, or in reverse etc). But had higher speeds, the MPG calculator triggers off something else that occurs at a lower frequency (such as a certain amount of fuel consumed). If this is what the MPG calculator is doing, it's absolutely absurd! First off, you will end up with way more "bad MPG" samples than "good MPG" samples and that will throw off your math. Secondly, you're treating the "timer pop" sample as carrying equal weight as a sample that was collected when you were actually driving! (When in fact the timer pop sample consumed far less fuel than a normal sample, and inherently should carry less weight.) In short, it's totally invalid to be doing the MPG calculation based upon a timer pop methodology. Tell me I'm wrong about what's going on here... But I believe I'll be able to prove timers are at work here sometime next week.

tdm1995

this is happening on MMI version MHI2_US_AUG11_P0533. Maybe there's a bug fix? Just backing out of my driveway reduces Long-Term MPG by .1 mile (on an accumulated 35 miles in long-term memory). The math makes no sense. If this is not a reporting bug, then my car is really suckin down the fuel when at ~idle. Is anyone else noticing this?

BobaPanda

As long as the engine is running your MPG will continually decrease. I haven't seen any inconsistencies between the long term MPG rating and what I get when I fuel up every time. I use Fuelly to track and it's usually accurate to +- 0.3mpg which is pretty good. I don't get what you mean by timer pop? The trip computer is dividing your miles driven by how much fuel is consumed. As you can imagine, if you car does not go into start stop while you are at a light or not moving (only occurs when engine load is low, IE no A/C) then your MPG will keep decreasing drastically since miles driven is not increasing but fuel is still being consumed by the car. If you are driving on a highway at a consistent speed, your MPG will go up, if you are in traffic and you have to accelerate and stop a lot, your MPG's will go down since accelerating uses a lot of fuel. When I just pull out of my driveway, my MPG's are often sub 10 MPG, until i go on some stretch of road where i'm not just braking and accelerating. 35 miles in long term memory is peanuts, once you get to 100 miles driven or 200 miles driven, then your backing out of the driveway will not effect much. Assuming 35 miles in long term memory, and you're getting 25mpg, you're barely at 1.4 gallons of gas consumption meaning backing out of the drive way will decrease that.

I also have a 2016 A6 2.0T P+ and have tracked 20,000+ miles.

tdm1995

Panda - i certainly hope in my case, there IS a problem with the long-term memory MPG stat. Cuz my accumulated 35 miles of long-term memory -- they're mostly highway. Cleared long-term stats at the beginning of my 1st formal measurement test (started a couple days ago). Anyway - long term memory MPG is now at 20.5... and dropping. I put up my post cuz I noticed - while on the highway, everything was lookin ok - but then it seemed little trips were having more of an effect on the long-term average than they should have. Scratched my head and came up with this theory about sampling on a timer basis - rather than on a fuel-consumed basis. I'm certain my long term mem MPG (on this tank of gas) will end up in the mid to high teens.... will compare that with a manual calculation on next fill up. Does anyone know if "realllly really poor MPG" is a warranty item? (Maybe mass airflow sensor?) I am retired, do mostly pretty short trips - in the City -- but dang I expect at least 22 MPG and am sure the long term mem is gonna be at least 20% down from that mark.

BobaPanda

I don't think that low MPG on short trips is out of the realm of possibilty... i'm a very very light footed driver and try to maximize my mpg's and have averaged 27.2 mpg, accelerate like a grandma and coast as much as possible. I usually get anywhere from 25-30 mpg on my car just depending on how much driving I do on the highways. Do you use start stop in your car to shut off engine at lights?

It's certainly not out of the realm of possibility to end up at low 20's or high teen's with this car. Obviously cold climate can effect the MPG quite a bit as well. What car did you drive before the Audi? If all you do is short distance trips you should expect a much lower mpg. For comparison, I had a 2013 Honda Accord LX before this Audi and was averaging 33.7 mpg on 10k+ miles tracked, so i've lost more than 6 mpg since switching over.

2016 Audi A6 Quattro MPG - Actual MPG from 24 2016 Audi A6 Quattro owners

tdm1995

Did anyone read where I purposely biased the car on this short experiment with Highway miles? And yet - the long-term-mem MPG stat is still gonna end up in the teens? I would like it if an audi engineer would respond.

Tom Moore

some addl questions for these audi instrumentation people:

1 - why do you even bother to record MPG samples when the car is in reverse? A: Yep we do it. t's meaningless and probably screws up the algorithms.

2 - why do you even bother recording MPG stats within the 1st (say) 30 seconds of firing up the car? A: Yep we do it.. It's meaningless and probably screws up the algorithms.

3 - CRITICAL: do you use a standard sampling frequency and treat it equal to other samples, even if the car is basically idling? A: Yep we do that - and we don't know how much it screws up the algorithms.

4 - Are You guys are really good at distinguishing meaningful stats from noise? A: NOPE! We have no idea on that!!

that's my summary of my 1st week with this car.

Tom Moore

I'm predicting (if you can't guess) - that the Audi A6 2016 Long Term Memory MPG calculation is gonna be off by about 25% for my driving situation (as compared to a manual calculation). My driving - mostly city; not heavy on the gas -- and am avoiding sport-mode shifting during this critical measurement period.

The A6 MPG calculator is coming up with horrible numbers for me (16 to 18MPG) - so it's not in Audi's interest to have a bug of this sort for city drivers.

There is the possibility, though, that my A6 has a serious MPG issue at low RPMs - and the computer is actually telling me the truth. But dang!! The car does fine on the highway (30-34).

My bet is --- some freakin computer geek screwed up the math for city drivers (sampling frequency thing) -- and the long term reported MPG is just way off from reality. In a bad way. If so, PLEEEZE - Audi -- let me know how I can help you improve accuracy. And how much you'll pay me to improve accuracy.

My final report will be delivered once I'm close to having consumed this 1st tank of gas. Late next week perhaps.

audi bug

Why don't you wait for a tank of gas to use up before worrying about the long term fuel economy?
Then you can compare with the published fuel economy for your engine (2.0L) and driveline (Quattro or CVT?).
You are observing long term fuel economy like an instant fuel economy.
Most of gas is used when accelerating.
No Audi (or any other automotive companies for that matter) engineer will answer questions in internet forum.

Tom Moore

because i already had a fractional tank of gas that has indicated to me what i'm gonna see. It's gonna be 15-18 --- and that is not acceptable.