N/A to be more specific.
So I have recently done a few things that have helped my car run a little smoother and was astonished by how many more miles to the tank I am now getting. I'm curious as to what's the normal average. I was getting about 198-200 miles a tank.

I cleaned some plugs to the harness for the coils and CAS, tweaked my TPS and lowered my idle. I just hit 248 miles to a tank tonight. I'm measuring this as a full fill up then running till the needle hits the black between the two fat orange lines above e, so I'm making my measurements using the same amount of fuel each time.

I realize that there is still a gallon or two left but to go from roughly 200 to 248 without changing my driving style seems pretty incredible for a few minor tweaks. The car seems to idle a bit smoother but not enough to explain this. Might be worthwhile for everyone to do a little contact cleaning and tune up. Get you a few miles extra between fill ups.

 

Nice numbers, my car has 119xxx miles, and it must have been taken good care off cause my low mile tanks are 215-220 miles and my high end is 270-300 miles per tanks. But normally i average 18-19 mpg. Car is s4 na, only 'mod' engine wise is a test pipe instead of the stock cat.

Edit: Forgot to say i fill up when my needle is below the double orange lines, so about 14-15 gallons a fill up.

 

I used to go 320 miles before my fuel light would ding on, then i could go another 30 before id really worry for fuel.

Car was a 88 SE base that i had swapped the hubs and brakes out to GXL/Vert/Turbo equipment, usually ran 205/55 R15's @30psi.

No PS, AC, manual crank windows, no sunroof, no rear wiper, no emissions. Exhaust was completely chucked in favor of a Racing Beat Header/Presilencer and then ran 2.5" piping to a single exit magnaflow muffler. I also had a ford taurus Efan and an exposed cone filter sucking in hot engine bay air, as well as no factory undertray.

Also had an Apex'i SAFC II that I used to tune out (be feel as I didnt have an AF gauge setup) fuel all across the RPM range (though mostly around idle and lower RPM's). Also had a fairly lead foot, and even got the same MPG's running hard on the dragon (us129) leaving it 2nd gear for the 11mile stretch of curves.

Edit: I also changed both my plugs and O2 sensor every year, never once replaced the plug wires, though I did keep the engine bay pretty clean with multiple power washing sessions over the summer and at least once during the winter when it was daily'd

 

The gauge is not accurate. Use this method instead:
1) Fill up the tank all the way.
2) Record the odometer reading or zero-out the trip meter.
3) The next time you fill the tank, record the number of miles driven and the amount of fuel needed to fill the tank all the way again.
4) Divide the number of miles by the number of gallons to determine the miles per gallon.
5) Search for one of the hundreds of gas mileage threads already on this forum.

 

with a full tank it makes 140 to 160 miles a tank. so sad!!!!!

 

is that normal driving or miami driving?

 

when my car was na it would get 19mpg around town and sometimes get 23-25mpg highway, confirmed by mileage and fuel used not the gauge

 

Jeez^ what kinda mods you running? How often do you guys change your fuel filter? I'm going on about 2 years since the last change might be due again.

 

That was for the guy with 160 to the tank! You guys ninja slipped in some posts before I responded!

 

Fresh platinum plugs seem to have the most effect on my mileage, beyond the driving style.

OTOH, I *have* passed tailpipe sniffer for the last several years on the same set of plugs.

 

my last S4 would regularly do 280 miles before the light would come on, the most i was able to get was about 300.

actually to go the other way, 280 miles using 14.5 gallons of gas is 19.3 miles per gallon

 

Wow, there is some awful mileage in here. Tune ups all around ASAP!

In my 87 TII (120k at the time) got 355 miles to the tank on 1-10 heading from Tallahassee to Batton Rouge). Mods at the time were cone filter and RB catback. In town I got 17mpg consistently under normal driving conditions.

Since then I've added an Rtek 2.1 downpipe and 720 secondaries. I now get roughly 230-260 miles to the tank with all city driving . Unfortunately I only get about 270-280 miles to the tank on the highway. (pretty sure the lower secondary staging point is to blame).

So if you're puttering around in an n/a getting less than 16/22 city/hwy you should be ashamed.

 

thats miami and normal driving. i try to go slow on the throttle because is too much gas. I am spending 60+ on gas weekly.

 

when i first got my s4 in 2004 i got 170 miles to a tank. just horrable. after gutting cat new exhaust plugs fuel injectors and doing a auto to manual swap i see around 240 now.. Not that great.

 

Dam... I searched for "winter mpg" because I was worried about pulling 19's instead of 21's this winter.

I can do 25-27 on freeway trips, and my average is about 22. Most of my driving is highway though.
This might hurt:
https://dl.dropbox.com/u/5310442/198...%20mileage.xls

Street ported, atkins 6 port sleeves, RB header + presilencer

Also... everyone should pay attention to Evil Aviator's post about how to calculate your mpg. Per tank is so varied and it's practically a pointless measurement. The gauge is below the double lines when it still has almost 4 gallons (1/4 tank) most of the time for me.

 

I've gotten 390 miles on all highway driving on a full tank in my s4 na, that's my best.

Full exhaust, streetport, etc and some weight reduction.

Rotary >Pistons

 

If I would of used the entires tank on my best mpg tank, I could of gone 448 miles

 

This thread would actually make sense if "TANK" was defined.

 

City driving not so good. The max i got on a long road trip was around 380 miles.. Best i have seen so far. thats s4 1988 gxl manual NA.

 

448 is kind of hard to believe.

Rotary >Pistons

 

if you used ALL 16.6 gallons, its 26.9mpg... if its 16 gallons you need 28mpg...

 

Exactly, plus aren't s4 tanks 15.5 gallon and s5 16.5.

This thread being about s4 only , someone shouldn't be posting numbers from s5.

Rotary >Pistons

 

It did 347.9 on 12.883 gallons of gas. That equates to 27 mpg. It's a 16.6 gallon fuel tank. 16.6 X 27 = 448 mi

Sure there is some margin of error, and I'm assuming that I'd be using my last 3.8 gallons of fuel as efficiency as my first 12.8, but when you do the math, you don't have to believe in anything.

You probably would have done more than 390 unless you were almost out of fuel when you filled up.

On road trips I typically just fill up anytime I'm below half or quarter tank and it's convenient.

 

well **** if you want to be specific...

347.9 mi / 12.883 gal = 27.0045796786463 mpg

27.0045796786463 mpg * 16.6 gal = 448.276 mi

It's 27 and I'm proud.

You are using my rounded number of 448 and so are getting 26.9879518... which you would have to round to 5 decimal places if you wanted to say it was under 27

sorry... I'm a math major



My original owners manual out of the glove box says 16.6 gallons. It actually might be 16.9 but I can never remember.

It's a 1988 vert

 

S5's have 18.5 gallon fuel tanks, aka 70 litres (I'm Canadian, eh)

I know this is about s4's but I find it odd that I achieved 31mpg on the highway once (300kms and filled up for 23 litres or 187.5 miles and filled up 6.1 gallons) and got 30mpg another trip, same highway but I could not for the life of me get more than 300-350kms (220 miles at best) before my fuel light is on and even then I still drive for a bit before filling up in the city with a bit of highway which equates to about 13 mpg which is I assuming I have 1.5 gallons left in the tank.

Even if I drive slow and barely rev past 3-3.5k I still achieve 12-14 mpg city/highway mix/ What could cause such terrible city mileage but great highway mileage. I've changed the plugs and the fuel filter already and it can't be the thermostat since I'm almost never driving fast enough in the city for it to be in closed loop. I'm never in 5th gear, sometimes if I'm lucky.

All this in my 1991 N/A with only 105,000kms