I am just currious about what setups are getting what mpg.

I was hopping some others would also be interested to know.

Please post your engine size, transmission, rear gear ratio, and tbi, carb, or multiport along with your avg mpg.

 

305, auto, lg4

14 mpg city
22 mpg highway..... yuck

 

I got 21 on the highway on my fresh 406 with a 240 240 cam. I was pretty happy with that. I didn't even have highway mode engaged. See my page for mods

 

that's pretty good for a 406 with 3.70 gears

Dingley do you know what gears you are running? How many miles on that 305?

 

i'm in obvious need for a tune-up.... 130,000 miles, 2.73's

 

355cid with 24# injectors running on 305 programming
3.23's
tpi
gave me 18 overall mpg. Since then I've reprogrammed for 22lb injectors and eventually for 24; haven't tested yet. I just want to develop a history to see what works best.

 

Note sig for mods. 22 to 24 on the highway with a high of 25.2.

JamesC

 

Interesting so far it looks like the manual gearbox makes the biggest difference as far as ecconomy goes.

James C what gear ratio are you running?

 

3.23s.

JamesC

 

7 mpg on the high way.. stock q-jet, AC Delco 305 motor with 15k miles on it, rebuilt trans with stock ratio, and stock rearend. filling up 2-3 times a week and having low hp sucks..

 

My 86 Iroc just got 32 MPG on sunday!
305 LB9, 4 speed auto, 3.23, fully loaded

 

v8 305 TBI
5-speed
i'm not sure what gears

I get a bit above 17 city, and with improved manual driving skillz, i'm getting close to 18-19-20 this week. Neutral is your friend, and red lights and stops are your enemy

 

25 mpg for the 87, L98-auto-3.27's-13x,xxx miles. 23 mpg for the 92 , LB9-auto-2.73's-147,xxx miles. These are all highway miles.

 

i get about 20mpg in city stop-and-go crap

30-34mph on the interestate. and the more i nail the tuning on this , the better i keep doing

setup is in the sig.

 

Got about 20 mpg on the highway a couple weeks ago. RPM's were at 2,800 to 3,000... setup in sig.

 

355, ported to death(PTD) TPI, Perf RPM heads, XE262 Cam.
Commander 950, 24# injectors, 3800 Lb. Car.

2.73 gears, 700R4 (.73:1), 26" tall tire.

2000 RPMS = 87 MPH, 10% Duty cycle inj. (10% of 24pph @ 38PSI X 8 = 19.2 / 6.3Lb/Gal = 3.04 GPH/fuel ) = <b>29~MPG</b>

1800 RPMS = 75 MPH, 8% duty Cycle inj. (8% of 24pph @ 38 PSI X 8 = 2.4GPH/fuel ) = <b>31.25 MPG </b>

this from datalogs, and its getting better as i tune further.
this after only 1 week of tuning....

 

hey, I have a 305, TBI, stock rear, auto stock tranny, and 130,000 miles on my car and I get like 7 - 12 MPG... and thats a mixture of city and highway... more highway then city. -- 7-12 -- YIKES that don't look good. cost too much too..

 

hey, I have a 305, TBI, stock rear, auto stock tranny, and 130,000 miles on my car and I get like 7 - 12 MPG... and thats a mixture of city and highway... more highway then city. -- 7-12 -- YIKES that don't look good.....

 

constant 16 mpg(get 200 miles to almost 12 gallons every time)
305 TBI LO3. mods in sig. mix city/highway driving. mostly highway speeds(55-60mph)with a few stop lights. stock rear(3.23 I think)

 

I've got a 91 firebird with 305 TBI auto trans. and I get about 17 MPG in the city and about 28 MPG on the highway. It says that on the window sticker that came with the car but it remains true today even though it has 149,739 miles on it. Still runs like a dream

 

'88 Iroc: 5.7L TPI/A4, 2.77-- 25.5MPG Hwy
'91 RS: 5.0L/A4, 2.73--27 MPG Hwy.


Ed