I got about 21-22 city. Tried my best to stay out of boost. Stock S4 turbo with K&N filter, 6psi on stock turbo and tune.

Driving on and off boost, some tame some enthusiastic driving. I got 253 kms to 60 Liters of gas..... Completely piss poor

For the americans thats about 158 miles to approx 15 gallons of gas

always 2 ends of the spectrum here. rotaries get horrible fuel mileage in town but can get decent highway mileage.

my 23.5mpg highway is negated by the 13mpg i get in the city. no amount of tuning has ever been able to get much better nor do many of the cars i put together get decent city mileage, it's just the nature of the beast.

S4 NA with 60k.
I average around 20-ish highway. However, my in-city kills me as my entire town is situation on a hill/cliffside. I actually do not want to know my in-city is :s Although, one of these days I should calculate it.

(this is a modified S4 running pig rich on a stock ecu as well)

i did some testing on the vert, and basically i separated the driving into 100% city and 100% freeway, and it'll do 30mpg @60mph with the cruise control on, but it only gets 12mpg in town.... so i average 16-18.

how in the world is 30mpg possible.. that's better than what mazda claimed :scratch:

i believe you and everything, it just seems crazy:dunno:

Mazda's mileage claims were based on EPA testing cycle that include real-world elements, not a theoretical ceiling. His test was more like a best case scenario, science experiment. Same as hypermiling will blow away a manufacturer's mpg rating.

I did 27mpg following a friend's race car trailer at 65mph for 4 hours. I was bored out of my mind, but I did it. Then proceeded to get 9 mpg at the track. So again, 18ish combined. :D

the stock maps are rich, in order to keep the catalytic converter from burning up.

i do think that most people who are claiming high 20's and low 30's aren't doing calculations properly though. like tire size offset causing mileage to increase, it's not alot but it is enough. i say that because even perfect running engines, taking out 20% fuel at most should not be bumping up gas mileage over 10mpg.

i calculated my mileage with a GPS and several trips over the same stretch of road, averaging out the amount of gas i could squeeze into the tank. leaning out the maps, increasing the timing nothing gave more than about 25mpg if i was really babying the crap out of it.

up to 25mpg is respectable for a car with 350whp with a step of the pedal, 30+ i have a REAL hard time believing. i've done a few runs where i had high 20's, then i realized it was just me and that the pump didn't push as much gas into the tank making me think i had another gallon left, so a simple pump can easily make your readings off by 10% or more by shutting off early. using averages over numerous tanks will correct this issue as will a GPS giving you accurate miles driven over speedo errors caused by non-stock size tires.

it would be much simpler for me to claim 27mpg when i made one trip and came up with that figure. reality is though that 23.5mpg is my average for strictly highway driving and that is what i claim, because i'm not fooling myself. and as soon as i have to start slowing down that gas mileage starts to take a hit severely, unlike just about any other car i drive. the BMW is heavier yet still gets close to 20mpg in the city and over 30 on the highway and it still has all emissions.

^This * 100

^I was giving a best case scenario, one shot deal, in an S4 NA. Sorry if I wasn't clear by my description. It was originally 29mpg, but then I factored in my 205/50/15's and dropped it down to 27. I don't do enough pure highway driving to have an accurate feel for it.

It's impossible to get a percentage of highway/city exactly right, so a 100% highway is the best comparison. City layouts, block length, traffic, light coordination are going to have an effect. Your analysis of city driving nailed it perfectly. Just the nature of the beast. :icon_tup:

roughly 16-18 mpg with my all stock s4 TII

I did once record 27.1MPG when my red car was a base auto all stock, with 185 wide phone dial wheels..

That was on a trip to Seattle [~4.5hrs each way and some city driving there], I made it there, drove around a few days and then got halfway home on one tank. Probably 150K on the original engine, full emissions, all stock exhaust, two passengers and all our clothes and computers for 3 days..
Though, my gauge reads about 5MPH below at 65MPH [65 reads as 70MPH], that's 7.69% low.

So the corrected economy for that trip was 25.01MPG.

This is probably where we get 30+MPG reports, from the [awful] speedo reading: 30MPG minus that 7.69% is only 27.69MPG.

I was averaging about 8-9 mpg on my setup, but thats getting on it and having some fun. im happy with that for my setup.

I drove 100% highway for 3.5 hours. Did 310kms on a half tank. That would be roughly 21mpg. I did no more then 70mph along the way and stayed at 60-70 the whole time. I have a a '91 NA with 60,000 miles with an exhaust and intake and don't see how some get this so called 28-30mpg. Wouldn't averaging 30mpg on the highway get you nearly 900kms on a tank. That can't happen on these cars.

If I keep my foot out of it, I get 10 MPG! LOL!

Something sounds slightly wrong on your car...

Replace the O2 sensor, spark plugs, check timing, clean injectors...

Stock S4 NA, rotaryworks 2*2,25" header, 3" exhaust, removed emissions, no ps or ac.

Lowest i measured was 24mpg, but usually i get an average of 20mpg on a tank. But the exhaust smells like unburnt gas, so i will see if it doesn't improve after installing a PFC and getting it tuned properly. Either way, the extra mpg is worth it, when the option is to drive an econ box...

Filled up a few days ago, then drove 50kms and filled up again. Filled up for 10 liters which equates to about 5kms per liter or 12mpg. I drive 100% city and do enjoy WOT on a daily basis, but seriously? Considering selling the car now. I'll replace plugs and wires when I have the money and the o2 sensor as well. I also think I have an exhaust leak, so I'll fix that too and report back.

I actually average 27 going from Pittsburgh, PA to Rochester, NY (5 hour drive).

NA. 75k. Full exhaust. Cruising at about 70-75mph.

When I brought my '90 GTU back to FL from TX a few months ago, I averaged about 26-27 using 89 octane. I think I even passed the 400 mile mark on one tank..

It had 68k original miles and was bone stock except for cat removal. I'm planning a trip up to NC next month and hoping to see over 30mpg after doing a full tune up. Car was pretty light from the factory being a slicktop and I've lightened it a bit more too (AL hood, vert BBS, etc.)..

27highway, 75-80mph, high teens around town. 87 octane

'90GTUs. Mild port on 5/6ports, helps the upper RPM's a bit while keeping stock torque and fuel economy. Nice blend.

I bet it would break 30 if I could stick to 65mph ;)

'88 GXL mostly stock, except for deleted main cats and aftermarket intake (both done by PO). The tires are also 225/50/15 and 195/50/15. I've been getting pretty consistent low to mid 18's MPG trying (with moderate success) to be conservative. About 40/60% highway/city. Its been ridiculously hot since i've owned the car, so 98% windows down with an arm hanging out to create considerable drag. I suspect some additional rolling drag from the wider rear tires. Should be getting an new compressor soon (and summer ending) so windows up, along with new tires (hopefully wheels too.) I'll update if the mileage improves.

Will new spark plugs alone help at all? I only got a small pay check and can't afford anything else. But next pay I'll be able to change plug wires, fuel filter, clean injectors and replace all oils.

What else could I do to make my fuel economy go up? I just got a fuel filter. Just give me a list of things that would help. Thanks.

Drive smoother and slower, install a standalone ECU and have it tuned by someone who has been doing it for a long time.