I get around 230 miles per tank. And that is with my fuel trims maxed out because of my pain in the butt computer. I hope once I get all of those issues fixed I'll get more then 230.

 

Are you sure your filling up the WHOLE tank? I thought I was having problems the one time I got like 130 miles on one tank, but that was before I realized how off my gauge was. Fill it until the needle is about about another 1/4 tank past the full reading or more. If you are doing that and getting 150, somethings wrong.

 

Agreed. I hate how I get like 100 miles in the 1/4 inch or so it goes past the F and the F. Then I get like 50 from half tank to empty haha.

 

You have to understand that you get like 80% of your gas mileage from the first half of the tank. The tank is odd shaped, meaning its wider at the top and thin at the bottom. I get about 240 miles and will have just above half a tank then about 100 miles from the rest of the other half tank. Thats Highway miles. Running 80+mph constant.

 

Have to debate what "city" driving is too. In NJ I deal with real stop and go. Distance from light to light or stop sign is measured in yards in many places, not miles. I get 14 ...ish mpg.

 

Welcome to New Jersey

 

LA in California is pretty bad too man. ha ha ha Thats were Im at

 

Doubt that is going to help or hurt your fuel economy situation.

 

You gotta remember the 98+ f bods have a slightly bigger fuel tank if im not mistaken. Im thinking 16 and some change - where as I believe the 93-97 has a 15.5 or so.

Running to about empty i get about 260-270 - thats maybe 50/50 hwy and city driving - a4 3.23 I think around 17mpg - 24 is where my averages are when I check it - the 24 would be a hwy trip (usually 80mph or so)

 

93-98: Steel tank, 15.5 gal
99-02: Plastic tank, 16.8 gal

There's a thread or two somewhere on swapping them out (for weight savings purposes, the plastic one is supposedly about 10 lbs. lighter), IMO definitely not worth it unless you've got a lot of time on your hands and ran out of other stuff to do.

My mpg is ~17.5, 75% city and 25% highway, of course I don't think the 3.73s and the 315/275 tire combo is helping very much. I've probably lost several mpg from said mods.

Back when I had my LT1 I would average only 12 mpg sometimes in city driving in North Carolina. A lot of lead footing and short driving cycles will drop mileage in a hurry.

 

You have a problem. Me thinks you need new plugs and/or wires or you have a burnt wire. You should be getting at least 180 around town.

 

OK I scanned the car while driving and at idle for a while yesterday. Not one code came up!! If my plug(s) and or wire(s) were bad wouldnt the car run rough? It runs very smooth and stong!

 

That little quirk about the cars has always annoyed me. I wish GM Would have properly calibrated the damn fuel guage.

 

Pull your plugs and read them. See if you're getting excessive carbon on the spark plug because your running so rich.

Clean them off...drive for a few days. Pull them out again. If they are CHARCOAL black, more then a usual spark plug running at stoich, then you know you're running too rich.

Did you check your AFR when you had it at idle, and did you drive it around to see what it looked like when under load?