TT-S4

I have not read my manual fully about the fuel gauge.
I have the standard gauge cluster.

I don't like the LED type gas gauge because I can't see/tel if the level is closer to the top of the LED mark or the bottom.
Tank fuel capacity is stated to be 15.3 gallons/58 liters.
Our gauge has 9 LED's, and that divides the fuel level into 1/8 of the tank's capacity.
Each LED is around 1.91 gallons, or 7.25 liters.
This would indicate that the LED right before the empty LED means there is about 1.93 gallons of fuel left.
It looks like it glows white at the top of the range, then turns red indicating "low fuel level", and then starts flashing red when it's about empty.

I wanted to verify how much fuel is in my tank when the "miles left" showed "0".
So, when I got down to the red LED on the fuel gauge I drove around staying near gas stations.
When the 'miles left' reached 0 the red LED started flashing, and I got a screen message on the gauge cluster to "immediately" refuel.
Took the S4 to the gas station and filled it up to the first auto-shut off of the pump.
The tank took 14.1 gallons.
It seems that the red LED and 0 miles left, indicates that there is only 1 gallon, or less, of gas left.

Next observation.
During this test, about as soon as the red LED started flashing on the fuel gauge I filled the tank and it took 14.1 gallons.
When I filled up the tank, there should be around 15.3 gallons of fuel, as that is the stated capacity.
My "miles left to empty" display showed 405 miles.

However, the best MPG I've achieved with my S4 is about 22.5mpg.
At 22.5mpg, and 15 gallons of gas, that would be around only 338 miles on average, not even close to the 405 miles the computer stupidly guesses at.
Programming in that much inaccuracy is ridiculous, and suggests the inaccuracy is done on purpose.
Why? I don't know why.
It's not like I'm going to be constantly fooled into optimism such as, "YES! This time I'm going to get 405 miles!"
What this designed inaccuracy does do is **** me off, because I know I won't get that kind of MPG.
The computer's programming should be able to freaking calculate an realistic prediction, which I can easily do with simple math and past MPG averages.

Showing 405 miles at every full tank fill-up is way overly optimistic at best, and stupid in fact.
That completely false estimated mileage is thus worthless.

When I last filled my tank to full, I got the 405 mile range estimate.
I've driven 70 miles since then, and the miles left now shows 286.
405 - 286 = 119.
119 is not equal to 70, not even close.

Given that the computer itself has calculated, and displayed, an average MPG of 22.5 over the last 3-4 tankfuls, then it should
easily be able to estimate that with a full tank of 15 gallons times 22.5 miles per gallon, the estimated mile range
would clearly be about 338 miles.

Why even have such completely misleading and useless "information" displayed.
The estimated miles left is so inaccurate that it can easily lead to someone running out of gas if they trust it.

The gauge is acceptable, even if inaccurate.
But, the "miles left" indicated is useless, thus pointless.
It's nearly 2020 and and even a high tech auto maker like Audi still can't create a fuel gauge that is even mostly accurate, let alone near exactly accurate.
And it's not just Audi because BMW, MB, VW, Honda, etc. don't fair much better.

nicotino15

I agree, both the miles left and the gauge itself are not very good. My total miles left is always like 380 or 390 which of course I never every come close to, I really wish it would take previous driving conditions into consideration and do some type of averaging to better estimate it, but I since that probably wouldn't look nearly as impressive as 400 miles left it doesn't do that.

TT-S4

LOL! True.

Yes, I agree about how it "should" work better.

danktastic1

my question is, how the hell did you get 21.5 mpg?? i get 17.5 while being cautious!

India Whiskey Charlie

LOL! Same here, although I am starting to see averages of 19-20 mpg as my car racks up more miles.

jondin2000

my question is how the hell u get such a low gas mileage? Are you driving on 3rd gear all the time....bc when I drive cautiously which is like 5-6 times on S mode in a gas tank I get 400 miles and there's still over a gallon in a gas tank

danktastic1

i just got a 19 s4 and the gas mileage has been horrific. i BARELY put the card in s mode idk if somethings wrong or not

jondin2000

I don't know how many miles on your car... my car it took like 3000 miles before I got the gas mileage I'm getting now

danktastic1

just hit 500 so im guessing it takes a while to even out..

TT-S4

LOL!
I understand.

And now, for my long "winded" response style.
You've all been warned.

As you know of course, any individual MPG is dependent on multiple factors.
Listed in my order of affect on average MPG:
- driving style: aggressive, sport, commuting, smooth cruising, grand parent, etc...
- mileage driven in: city, suburban, rural, highway, percentage mix
- along with the above, how much stop/start traffic on a daily basis
- terrain: amount of hills and grade levels
- tire PSI
- average cargo weight
- tire type
- weather: colder weather typically gets a bit lower mpg average.
- accessories use: such as AC, seat and window heaters, charging devices
- and maybe other things as more minor data points.

I live and drive in the "greater Chicago area", as we call it around these here parts.
That means that people live 50+ miles away from Chicago; north, south, and west, and are still considered part of the "greater Chicago area".
Oddly, even those of us who actually live in the Northwest corner of Indiana, are still considered part of that greater area, but many city folk strongly disagree on that regard.
They'll just have to get over it.

I'm about 45 miles south and east of the city.
I do not live in the city, nor do I work in the city.
The terrain in the greater area is quite flat, with only occasional hills, such as the more rural area where I live.
My daily commute is about 36 miles round trip.
About 60% of that is on relatively level/flat and straight highway, and 40% suburban-rural where speeds are, on average, between 30 to 50mph with few stop lights or stop signs.
Also, about 85% of my miles have just me in my car, so a lighter average cargo load.
However, that is somewhat lessened as I am larger/heavier than the average bear.
I digress.

So for me, idling as the car is standing still is very limited.
My average speeds are higher than drivers who drive in the city proper, where there is a lot of stopping with longer intervals, and when going most drivers do the "gun and run" squid method to get around due to traffic density.
And when city drivers get on the highways in and out of the city, such as commuting to their suburban homes, they are often in heavy highway traffic where they move at slow speeds for extended periods of time.
Also, include all of the intervals on those highway commutes where they may be stopped numerous times.

For me, I have the luxury of open roads with fast moving traffic so I get better efficiency in miles per gallon, as I'm moving more miles for the given amount of fuel compared to the city drivers who live and work in the city, or the great number who commute into the city and have an 80 to 100 mile daily commute.
Given my driving conditions I can drive at higher speeds, and in a more spirited manner with bigger throttle input and enjoying higher levels of acceleration, while still getting decent MPG on average.
I also use higher PSI in my tires. I use the recommended "higher load" and/or "higher sustained speed" PSI, because the majority of my miles are highway and suburban-rural.
The higher PSI helps increase average MPG, and also gives lower tire wear.

Not everyone has those same conditions around the country.
Many places are hilly and thus naturally those drivers need to call on more torque to get to speed on hills, and to maintain speed on the varying grades.
Needing more torque on average means using more fuel.

For some other drivers they may drive in areas where there is more snow on the roads during the winter season, and that may require lower overall speeds while still having to use power to get through and over the snow.
Throw in a good amount of hills and varying hill grades and average MPG will naturally drop.

Using dedicated snow tires will affect MPG, as actual snow tires have a higher level of grip on snow, but when driven on snow free roads there is a big increase in friction due to the tire tread and compound of snow tires.
Add in consistent above 32F temps on snow free roads, and those snow tires have an even greater level of friction further reducing MPG.

I get decent MPG, and still get to utilize the S4s power because my driving conditions allow it.
If I were to live in Chicago my MPG would be much lower.
And if I lived in the city I wouldn't choose a car like the S4 in the first place.
I have a number of friends and family who live in the same area as I do yet they work in the city, so their commutes are longer and include some of that stop/go city traffic.

Additional interesting information:
Let me preface the following by stating that I do not choose these higher performance cars because I am concerned about paying for more gas.
I'm offering the information below strictly as observational and comparative.

I had a 2012 335i Msport, and then a 2016 340i Msport, both with the ZF 8spd AT.
With the 335i my average MPG was around 25-26mpg.
The 340i had the new BMW 3.0 turbo, which is higher efficiency, and I averaged around 26-27.5mpg.
For me then the S4 is quite inefficient, and the overall power and performance is pretty much the same between this S4 and those BMWs.
I drove all 3 on the same roads and routes, and in the same manner, so the difference in average MPG is quite telling.

The BMW were RWD and the S4 is AWD.
The increased friction is obvious, and a decrease in MPG is to be expected, as it is even with the X-drive/AWD BMWs.
Still, going from around 27mpg avg. to 22.5mpg is a huge decrease. It's nearly a 20% decrease in fuel efficiency.
The decrease can't be explained as being just the AWD system.