I currently get about 15 mpg. This is mostly city, and very lead-footed. It is also with a floor-sweeper rebuild I put together with used everything except apex seals. It also "idles" at 1500+ RPM. I have yet to drive it any distance on the highway with this motor.
Withe my old engine, which was a professional rebuild, I got damn good MPG. Lead footing it and doing fast back-road runs I never got below 18 mpg. My best ever was 28 mpg, and half of that was spent cruising at 85-90 with the windows down, with some in-town driving. I could have definitely pulled off more than 30 mpg if I had tried. This is with stock ECU and a motor with a largish streetport and ported exhaust.

 

Geeze man. I get 10city/17highway without a lead foot and a tuneup 500 miles ago.

 

I got 28.9 mpg the other day, coming back from college with a car full of crap. 110 miles used 3.8 gallons of gas. I too just rebuilt my motor (NA) and am at the end of its break in period. Never went over 3,800 rpm the whole trip. When I I got to othello from pullman and the pump said 3.8 gallons I thought the pump was broken, but I am continually getting high readings. Getting all the vac problems figured out, no AC, nice fresh rebuilt engine, and driving like a sleepy grandma will really help the gas usage. Also I was behind my g/f's volvo the whole trip, I'm pretty sure that helped a little. When I saw the mythbusters episode about how much gas you can save staying behind semis and such, I prefer to be in the back of the pack.

Also, I have noticed over time, since I have stopped speeding like an idiot, that just going the speed limit and keeping the throttle as still as possible has helped. I used to have a radar detector and would speed almost everywhere, keeping a lookout for the po-pos. Everytime I saw a car that might have been a po-po I would let go of the gas and even smash the brakes sometimes. Back then I never used to think about how bad that was really hurting my gas milage. haha

 

about 18mpg. probably will go down as I turn the boost up

 

Playing with the Microtech yielded me about 22-23 on the highway doing 75mph @ 3200 RPM. Combined city/hwy I get like 17-18.

I think the S5 has the larger fuel tank, so that's why some of the people on here can get 400+ miles to a tank.

 

I think my S4 GTU is getting better city mileage than my old S5 GTU which I guess makes good sense since the S4 is lighter. I generally saw 15 mpg city in the S5 and 23-24 highway if I didn't go too fast. That dropped about 1 mpg in the city when I put in a rebuild with a street port, maybe because I tended to drive with heavier foot? In the S4 I tend to see about 16 city. My S4 also has the "aero" package which supposedly drops the drag coefficient down to .29 from .31 or so... I wonder if this will actually help my highway mileage. I have yet to take this car on a long enough trip to measure a full tank of all highway.

Yes, the S5 tank is larger which would explain the longer cruising ranges but not the claims for better overall mpg.

Not calling "bullshit" Fumihiko, but I'd love to know how you got 33 mpg.

Oh, and it really makes me sad that my other car, a 2002 Dodge Caravan that weighs a good 1000 pounds more and has more power than my NA 7 gets a little better gas mileage. I think we know why the rotary never conquered the world.

 

Bone stock S4 N/A, best I've managed is 23 MPG.

But I usually average 17-20 MPG.

 

i had close to 30 mpg on freeways, and cities was really bad 8mpgs

 

I'm pretty much consistent in getting about 15mpg or less. No matter how I drive (quick acceleration and short gear shifts, slow acceleration and shifting at 3k, slow acceleration and shifting at 2k, quick acceleration shifting at 2.5k and 3k, you get the idea), whether it's freeway or city...

 

Same here, i got an S5 NA and driving like a granma i only get 13MPG and like 250miles per tank thats 18 galons, im considering trading the 7 for a bike lol

 

You definitely need a tuneup. If that doesn't help, AFC or Rtek, preferably Rtek, pull the O2 sensor, and tune for gas mileage.

 

S4 GXL 5-speed, my 36mile one way to work was 21.5, which is 50% interstate and 50% county road. So imagine my surprise when my wife and I ran I-75 from Cincy to Gatlinburg, 75-80mph, and she came in @ 26.

Nice.

 

Well i got vacum leaks, a check engine light, i got a new O2 sensor, and if by tune up you mean spark plugs and wires i did that too, i got anew fuel filter and did the injector cleaner (The gas mix), i need a new air filter but i doubt thall make a huge difference. By Rtek you mean an after market computer to tune the ecu? I was looking that up but i dont have 1k to spend on an ECU

When i do the check engine i get so many random errors, i just assume is a major vacum leak, i dont know how to deal with the rats nest should i just remove it like everyone else is doing? I dont know how to deal with vacuum leaks

 

I mean a piggyback. You can get the AFC Neo for $275 or the Rtek for $399. I think the Rtek is worth the extra premium. The Rtek will even let you skip the next step of what I think you should do.

PULL ERROR CODES! Find out what the hell the computer thinks is wrong with your car and fix them! The Rtek has a readout for error codes, but there is a method posted on this forum to find them if you don't have an Rtek. Go through each and every one of the error codes and fix them. Don't assume it's anything else. No one said owning a cheap FC was easy.

A vaccum leak means there's an air leak. Find out where they are and replace all the hoses/lines around it to seal off the leak. If it's a gasket leak from the exhaust, get a new gasket.

 

Automatics generally get lower gas mileage than manuals.

The compression ratio could explain the difference between S4 and S5, but I just thought of a reason why they could, in theory, get better gas mileage. They run a 3.9 R&P compared to my coupe's 4.1 and my GTUs' 4.3. My coupe gets better mileage than my GTUs so it could be conceivable that verts would get better mileage than my coupe.

 

Oh yeah, best mileage. My best was either 19 or 20mpg. Right now it's typical to see 18

 

yeah i get about 320 miles on a 16.9 gallon tank

 

yeah, S5 tanks are bigger.

my 10AE with the halfbridge got 25+MPG cruising at 90-100km/h.
around 15-18 in town.

 

i have an LPG turbo FC, 10 psi mild port
17 - 20 L per 100 Km LPG ( propane and butane oz mix )
( hard city driving, its considerably better highway driving )

or
4.5 to 5.3 US gallons per 62 miles
( 11. 6 to 13.7 mile per gallon LPG )


in real terms, its the equivalent of a 9 - 11 L per 100km city cycle
modern Japanese 2L using premium
or
2.3 - 2.9 gallon per 62 miles
( 23 - 27 mpg US petrol ) city cycle


there is also a few hidden advantages besides the octane rating
( its faster and smoother than you would initially give it credit for )
- and i have plenty of experience with hard tuned EFI rotary turbos
so i am a fair judge

simple impco 225 closed loop kit with model E converter , and 60 L underfloor tank