I have a 92 3.1, I recently took a ~240 mile there and back road trip, all highway going ~75 mph with no cruise, ttops off, 1 friend and camping gear...

I got 31 mpg...and was very impressed bc I could actually even do better than that if I wanted...

and this fueleconomy.gov is full of **** then...15city/25hwy...yea...
http://www.fueleconomy.gov/feg/findacar.htm

What's your mpg?

 

I average ~20 last time I checked. Half of my driving is higway and the other half is city. I live on the outskirts of town so I have a straight shot to town, then to go to my job I have to drive through the busy part of town in the morning. Most of my driving is with windows down.

 

Just over 20 in town, just under 30 highway.

Oddly enough, my TPI 87 Formula gave me nearly the same highway and 17-ish in town.

Back during 1.25/gallon gas I couldn't justify the little guy. Now, though...

 

I've only driven my car 1000 miles since Sept 06, but I know haow many miles I get to the tank. It's about 275/15.x gal mixed city, highway, and track. This was N/A with roller rockers.

If you want to boost your economy more, add 3oz of pure acetone to 10 gal gas. You will see at least a 15% in MPG gain. I have been doing this for over a year in some of my cars with no problems. Google it, you will see .

 

ok 92 3.1L I get 17 city and 28.6 highway. Car has CAI, 2.8L headers, high flowcat, 2 1/2" flowmaster 80 series cat back.

Dont forget this will be different on each of our cars due to elevation changes in our driving. some may only drive flat roads and see better gas milage and others such as me drive in a hilly more mountanious area and get a little worse milage.

 

You are right. Here in FL, we rarely see hills. Avg height is 2' above sea level.

 

I usually get between 17-18, And that all stop and go. I rarely hit the highway, but the highest mixed Ive gotten was about 23. There are alot of hills here in PA too. I think the lowest I got was about 12 but that was when I first got it.

 

lol i get about 200 miles per tank that a estimate since my gauge cluster does not work

 

Yeah but that in south FL. Up here in the panhandle there are a fair number of hills. Threre aren't many flat spots around here.

 

yea i forgot to add my car is 100% stock and in michigan so i drive some hills...

I was just really surprised to see a 15 year old car get that kind of mpg...and with the v6 you have to downshift and rev it to get passing power lol

 

Elevation average around me is 1000' feet above sea level. And the average loss of horse power is 3% for every 1000' feet above sea level.

hp loss = elevation x 0.03 x hp @ sea level
1000

 

I took a trip from southern Wisconsin to northern FLA last summer and got 26mpg.... 1000 miles down and 1000 miles back... 89 trans am 305 tpi.... LB9 engine....t-top ... even went through a tornado.... sucked the scoop portion right off my bulge hood..... wow!

 

I'm at 5000 feet. I do an average of 30 mpgs on the highway in my 1988 RS. Only 17 strictly city and 22/23 combined. I have a Flowmaster Catback and a MSD 6AL ignition. It has only 95,000 original miles. I run the lightest factory wheels, the GTA's and an alum 1LE driveshaft. I try not to carry unnecessary junk in the car. Every little bit helps with these micro motored cars.

 

Ever since I did the 3.4 swap I was getting terrible (by my standards) mileage at first. I went from 380 miles per fillup/28mpg to 285 miles per fillup/22ish.

My mileage has been getting better month by month and the last couple tanks I went 350, 360, 370. That's all city, county, and freeway combined. Elevation here is about 300ft.

So, 26-27 I guess.

 

So was this a rebuilt motor that needed to break in?

 

18 freeway =P

 

My T/A gets about 21 city and 36 highway 2.8 Liter V-6 MPFI swap from 350 TPI with auto trans. I'm in Lubbock texas, mostly flat around here. When I leave the caprock, I get about 18 city and 28 Highway.

 

Sounds great but I dont get it do you have a 2.8L that you swapped a 350 in or did you have a 350 and swap a 2.8L. And under your name it shows you have a camaro no a T/A

 

'87 2.8L - 9 MPG

Don't ask...

 

boy you must be going WOT or slamming on the brakes to get that type of number

 

a month and a half a go i had about 20 mpg average. today i checked when i filled up, 25, who the hell knows why but, im not gonna complain.

 

I believe warmer temperatures allow for better gas mileage

 

the temps really havent changed around me more than 5 degrees or so. and my driving conditions have gotten worse if anything. but the temp wouldnt change my mileage that much, and i get gas at different stations in a 50 mile drive to work. so i dont consider bad gas... unless theyre all getting bad gas.
today i just filled up and got 23.9XX miles per gallon. and this week i happened to be following a lot of tards driving 10 to 15 miles per hour below the speed limit so i did a lot of hard-accel passing.

 

It WAS a 350 but the original owner swapped it out for a 2.8 Liter (why? I don't know what would cause a man to do that to a Trans AM), and I just put in a new 2.8. I used to have a Camaro, but between transmissions and motors, we scrapped it and bought the T/A.

 

is it an authentic Trans Am or a very through clone?

 

I usually get around 22 in mixed city/highway driving. Last Christmas we ran through a full tank on the freeway, in the rain, on a very windy night, mostly around 75mph, to out beyond Palm Springs and back. I was pleasantly surprised to see 27.5mpg on that trip.

 

1989 2.8 5 speed before a tune up IE NGK Plugs, Bosch Wires, a few broken vacuum lines, no wire spacers, broken cat. etc.
450km to 59 litres. 7.5 km's per litre. So 12.06 MPG. Hwy/Cty.