squirrelishere

iTrader: (6)

Okay, my car has had these mods: K&N CAI, LS6 intake, Pacesetter long tubes, GMMG catback, !EGR, !AIR, and just recently found out I have 3.73 gears. After using 3/4 tank of gas, I'm sitting about anywhere from 120 miles, and sometimes 160 miles. Right now I'm at like 165 sitting halfway between empty and 1/4. Last time I filled up, I only got 135. I did spark plugs a few months back, checked my tire pressure, also sea foamed my car a few months back. I'm about to change my fuel filter, since I haven't done that since I got the car(about 3 years now). Would that regulate my gas mileage more? Or what could be the cause that sometimes I get low mileage and sometimes a bit higher?

Also, a more important question, with my mods, is that just my average gas mileage now?

ihaterice

it can vary mileage depending on how clogged it is, but usually it will make it worse all the time, but there are cases i have seen where the car behaves wierd like that. but there is a chance it could be the fuel pump too, has that ever been replaced?

FiredUpZ28

Fuel filter will help a lot. Its really easy to change too. Should be done once a year.

I wouldn't gauge your fuel mileage from anything less than a full tank (when the pump shuts off). My car is a 2000 and the fuel pump sending unit is funky. It dips down under full when it really has 3/4 tank left. I know this is a common F body, or GM, problem for that matter.

Gas mileage test. Fill up till the pump stops, record mileage. Drive around like you do normally. Next time, fill up all the way (I know its expensive) and see how many gallons it takes. Divide mileage driven by gallons taken to fill. Only accurate way.

squirrelishere

iTrader: (6)

Well, it took about 11.7 gallons to fill up my car from a bit less than 1/4 tank. I read online and since my car is a 98, it has the old 15.5 steel gallon tank.

Mr Incredible

165 mi divided by 11 gallons is 15mpg. With 3:73 gears and all those goodies that sounds like it could be normal.

Keep your foot out of it, no WOT, stay in your lane, and go the speed limit for an entire tank and then see what the best case scenario gets you.

For my no-bolt-ons, only have an opened-up TB and 3:23s with automatic...I can get 21 mpgs in town. Usually I just get around high 19s or low 20s.

For good gas mileage I just got an old beater CRX. 40mpg average, high of 52mpg, low of 31mpg.

squirrelishere

iTrader: (6)

I'ma have to force myself to stay at 25-35. My average speed is 40-45. I'll try that after I change my fuel filter.

I got my fiance a 04 Cavalier, so that's getting me the good mileage I need, but I just love my car too much to not drive it.

FiredUpZ28

i hear ya. Yea one of the best tricks for gas mileage DD'ing is to get the car in 4th/OD as fast as possible. I dunno how it is with 3.73's but if I want to cruise at around 40, get to 45 mph, let the TCC kick in, then drop down to around 40. Little things like that help a lot.

qwk93ta

iTrader: (13)

My 00 WS6 is bone stock A4 and I am averaging about 18 MPG. My 93 T/A M6 has tones of mods but if I keep my foot out of it I can get 19 MPG even with a 9" / 4.11s.

spazzyfry123

iTrader: (4)

Is that just an Automatic transmission thing? When I had my M6 SS with a few mods, I was averaging about 25 mpg and that was with me pushing the go pedal a lot too...

FiredUpZ28

well, those 2 overdrives help a lot. Sticks simply get better mileage also since theres no slippage like an automatic.

quickblade

That is where I sit.. I dont have the mods you do, but I hit 100 shot N2O, have 3.73's, and a tune... I get around 13 - 14 MPG...

Anywhere.. city streets and highway... actually I think I get better gas mileage under 50 MPH... anwhere above that.. I can watch my tank go down..

So you are not alone... LOL.

johnnydi

You might need to tune the computer with all those mods. I don't know much about that but I hear it makes a big difference. John.