TERRIBLE Fuel Economy

[DylanFulton]

I'm sure that this will come as a surprise to many of you, but my S4 is an absolute pig on gas. I've searched far and wide to narrow down a solution and I've had no luck. Over the past 4 months I've replaced my fuel filter, bank 1 pre-cat O2 sensor, cylinder 7 ignition coil, and cylinder 7 spark plug. (Only did the necessary maintenance given the winter months) I was getting about 175km/tank. After replacing said items, my mileage certainly increased. But it's still nothing to be proud of. Since then, I've had no fault codes and the car seems to be running just fine. Other than a random (slightly) rough idle I get now and again when the car is at operating temperature (perhaps related?) I now get 250km/tank on average. Granted, 90% of my driving is in the city. For arguments sake, I decided to do a couple of full tanks just on the highway to see how I compared. I managed to squeeze 380km/tank. I should note that all of these figures were of me driving conservatively, trying to use a little fuel as possible. Now, I knew long before buying this car that they weren't exactly fuel efficient. But, doesn't this seem a little excessive? Maybe it's just me... To the point, what sort of numbers are you able to get when driving your S4 conservatively? Any suggestions as to things I should try/check to improve my fuel efficiency? As always, any help is appreciated.

[Concavitor]

TERRIBLE Post

[emilio]

i get widely variable mileages, but i'm pretty sure that's normal; it's a relatively heavy V8 car with all-wheel drive, it's very sensitive to driving style. the miles i get per tank vary totally on where and how i'm driving: city-only with lots of stop-and-go and maybe i'll get 200mi/tank, but i can get 290-300mi/tank on a purely highway road trip (even at a steady 80MPH).

- emilio

[jakeoboy67]

5.0 f-150's usually get a better gas mileage than my car, lol .
but it depends mainly on your driving habits . . .


quick question : how much gas do you put in your tank when your gauge says "empty" ?
If your sending unit is starting to go bad, it might show a lower gas level than what's actually in the tank.

[Tinpusher]

My fuel gauge went on the fritz a couple of months ago. It goes from beyond full by 5mm to half tank and all points in between at any time. Distance to empty is still accurate and I got to 580km on my last tank with DTE at 30km.
If you're only getting 250km/tank and filling up with over 60 liters, you have a problem. Either there must be a leak (any smell of gas when you're parked?) or something is seriously out of whack with your engine.

[nogaroblu]

I get around 200-220 miles out of my tank, that's spirited driving on the way to work (80% highway) and bumper to bumper (hour at least) traffic on my way home, 18 miles each way

[Axel-]

I get 300kms with 90% city so you're not all that far off. Also, remember that winter gas won't get you as good mileage.

[DylanFulton]

Good point on the winter gas, I'm sure that'll have an effect to an extent. As for fill-ups it's always a full tank, so 60-65L. I know the cars gas mileage is hugely influenced by driving style, but like I said I've been driving very conservative (which is excruciating). That said, I'm still getting mileage comparable to some rather spirited driving.

[luislallo]

1-clean the egr valve or buy another one 2-the pcv 3-purge valve 4-suction jet pump ,after that you be good.

[Axel-]

Good point on the winter gas, I'm sure that'll have an effect to an extent. As for fill-ups it's always a full tank, so 60-65L. I know the cars gas mileage is hugely influenced by driving style, but like I said I've been driving very conservative (which is excruciating). That said, I'm still getting mileage comparable to some rather spirited driving.

Pretty sure out gas tank is only 63L. Putting in 65L might be tough.

[lucidmatt]

Checking in with 13-15 MPG city 18-21 MPG highway Its just a part of the territory.

[DylanFulton]

Pretty sure out gas tank is only 63L. Putting in 65L might be tough.

Edmunds lists the tank at 17.4 gal which works out to 65.866L. So it is possible, according to Edmunds...

[JimmyBones]

Checking in with 13-15 MPG city 18-21 MPG highway Its just a part of the territory.

Now that I have the stock sixth gear back in my SCed S4, this is around what I get too.

OP, check your tire pressures. I tend to run mine a little high around 40 PSI. Then I try to coast as much as possible when driving in the city. People get pissed because I will leave a big gap between me and the car in front of me and coast while the car in front is sitting still waiting at a light so that I stay moving.

[Axel-]

Edmunds lists the tank at 17.4 gal which works out to 65.866L. So it is possible, according to Edmunds...

I prefer official Audi documentation rather than 3rd party crap riddled with errors.

http://www.audiworld.com/model/s4/06/S4%20SE1.pdf

(See page 2 under the section "Capacities").

CAPACITIES:

Engine oil 11.3 qt. 10.7 liter
Fuel tank 16.6 gal. 63 liter
Cooling system 12.9 qt. 12.2 liter

[DylanFulton]

I prefer official Audi documentation rather than 3rd party crap riddled with errors.

http://www.audiworld.com/model/s4/06/S4%20SE1.pdf

(See page 2 under the section "Capacities").

CAPACITIES:

Engine oil 11.3 qt. 10.7 liter
Fuel tank 16.6 gal. 63 liter
Cooling system 12.9 qt. 12.2 liter

I stand corrected, Audi documentation is likely a more reliable source than Edmunds

[VinnysS4]

Checking in with 13-15 MPG city 18-21 MPG highway Its just a part of the territory.

yeah thats about what i tend to get. i can get 25 to 28mpg on the highway, but thats talkin grandpa driving and catching the wind from the semi infront of me. My RS6 got the same mileage as my s4. imagine that. haha and the new 2016 RS6 gets like 28 mpg. now only if i could get one here in the states....

[4point2]

this sort of thread pops up all the time, these V8s are thirsty at the best of times. throw in winter gas, traffic, heavy foot, yada yada, and it's not surprising to be getting terrible numbers. I get around 230kms to 3/4 of a tank (as i never go below a quarter full) so that would put me at close to 200 miles to a full tank. Mine is auto, it's an avant and i do drive like a jerk in stop go traffic all the time and then mat the gas EVERY CHANCE I GET

tbh if fuel economy is top of the list, then a more-than-a-decade-old technology, nearly 4000lbs, 350HP, AWD V8 car prob wasn't a good choice. just sayin'

[Durk]

I'll throw in my 2 pennys...
Best I ever did was 25mpg average all highway with cruise on, car was fully loaded with 4 passengers and luggage.
I tried the intake flapper mod and hooked it back up when I lost 1 mpg in my average (down 19 to 18mpg).

I've never driven a car that cries for gas like this one does. If I fill up as soon as my gas light comes on I only put 13 gallons in and it says my range is 45-50 miles left. Even at a conservative 18 miles a gallon that leaves a range of 65 miles before you are on zero.
I intentionally took it to zero and filled up to see how much gas was left and the car took 15-ish gallons.
Audi mind games....

[Terry.Reese]

tbh if fuel economy is top of the list, then a more-than-a-decade-old technology, nearly 4000lbs, 350HP, AWD V8 car prob wasn't a good choice. just sayin'

lol, so true. I saw the pig as she was.

[WCCoffey]

My car with a JHM tune gets around 8-10mpg city and around 17-18 highway.

My truck gets better fuel economy, makes almost double the power, and might even be faster... Lol

[cobraBLACK]

What sort of figures do you see on the live MPG whilst driving?

I have a manual Avant with no tune, only Milltek cat-back. When I've stopped accelerating and am in the right gear I see 30+ MPG on flat roads (I can get a max. of 30 at motorway speed (70ish) but nearer 40 MPG at 40-50 MPH). I get about 250 miles out of a tank (mixed driving) and 300+ with motorway runs included.

I do plan my journeys to stay away from traffic as much as possible though. For example, the route I take to work is slightly further than the direct one but involves faster roads and fewer queues so it takes about the same time as the shorter route but is better for fuel economy and better for the health of the car.

The S4 is not much worse than the wife's Suzuki Swift which has a 1.5 engine that needs the guts revved off of it to get anywhere.