I am curious as to how we are all fairing with our plastic bodied cars. Please list engine/trans as well as CITY/HWY mileage.

3800 Series II, 4T60-E

22 CITY / 33 HWY (actual)

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1987 Pontiac Fiero Coupe #18,838
3800 Series II SFI; 4T60-E Trans w/ 3.33 final drive; Terminator exhaust; 4 wheel vented disc conversion; Walbro 307 fuel pump; W-body air box w/ K&N filter; Rear 32mm sway bar; 134a functioning A/C; GM CD player w/ factory location sub; much more and...a stock GN's TURBO on the way!

Conversions Performed:

1985 SE 3800 Series 1 SC 4T60-E

1987 Coupe 3800 Series II 4T60-E

1987 SE 3.4 DOHC 5-speed (under construction)

http://dtcc.cz28.com

SEEEEEEEEEEE........ that's one reason I want a 3800 in my car. I never had a 2.8 that even came CLOSE to those figures.

I get 20mpg all round driving in my 87GT 2.8 with a 4spd 4:10 ratio.....which I guess isn't really bad. It's turning 3k at 60 mph.

Phil

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GTDude
OVER 25 years GM experience

I have a 2.8 with a th125 with the 2.84 final drive ratio. If I drive it nice and easy I can get about 26mpg and if I tear around town I get about 18mpg. When I had the old transmission in it I think it had a 3.08 final drive ratio I got much worse. I hit 3000 rpm's at about 85mph.

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-Chris
www.geocities.com/m60chris

1988 GT 2.8L built as a 3.2L with 440T4 with approximately 5K on the setup last trip it got almost 34MPG.

my odometer is not working. but I guess my duke is getting around 29 city and 34 hwy based on hwy markers and from knowing how many miles to my destination.

3.1 w/ th125
17 city
26 hwy (under 70 mph)

I just have average milage.

My 87 GT w 5 speed has averaged 29.5 mpg since day 1, 96,000 miles of driving fun.

My 88 GT 3.4L w t440 auto gets around 30 mpg. Its hard to tell, the odometer is reading low about 5-7%.

86 GT automatic 20MPG normal driving 25+MPG highway.
86 coupe 4 cylinder automatic 30MPG no matter what. It has gotten up to 35 MPG on the highway, unusual but it has happened more that once.
87 GT 5-speed, 25MPG city/highway, 30+MPG and up open road/highway.
The others (driven) are also above average I guess.

1985 gt/w 3.1l camaro 17 average around 21 highway under 70, as low as 14 highway REALLY pushing it.

'88 v-6 5-speed getrag
- 22'ish city / 29.5 highway
original 2.8 got 34 mpg highway all the time.

'87 4-cyl th-125
- 18 city / 25 highway(mpg drop as speed increases over 60mph)

My 1985 Fiero GT with the 2.8 and 3 speed automatic, I'm getting about 17-20 mpg I mean this is People on these forums with V8's in their Fiero's are getting better gas mileage!!!!

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Silver 1985 Pontiac Fiero GT
_____________________

88 GT 2.8 Getrag 36mpg at 70 mph.

I find 70 mph gives the best gas mileage. At 60-65 mph, it drops to 32 or so.

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1988GT T-Tops, 5spd, Loaded

86 2M4 auto
33.75 mpg hwy
lower in town.
See https://www.fiero.nl/forum/Forum2/HTML/018929.html
for more details.

3800 series II supercharged/4t60e

18-20 in town 29-30 highway

runs mid 11's

Stock Duke:

25 MPG City
45+ MPG Highway

The city figure is pretty accurate.. I calculate my mileage at each fill and most of my driving is in heavy downtown traffic.

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1988 Fiero Coupe 2.5L
1990 Trans Am GTA 5.7L

Wow.....I get 16MPG city with my 87 2.5l.....and i have noticed it missing a little...and a rich smell......and, no I havent neglected fixing this....its on my schedule to do this week but what is the normall MPG for the little Iron Duke with the automatic?

Hey,
For your Canadian guys. How many KM's do you get in city driving. I only get around 250KMS? What does this work out to?

Thanks,
Chris

quote Originally posted by 1985FieroGT: My 1985 Fiero GT with the 2.8 and 3 speed automatic, I'm getting about 17-20 mpg I mean this is People on these forums with V8's in their Fiero's are getting better gas mileage!!!!

You are damn right. It is impossible to get a v6 fiero over 25mpg highway. You're lucky if you can get that. I have had 3 GT's. My 88 and 86 get 20mpg highway and my 87 rebuilt gets 17mpg highway. My 86 gt had only 55k miles on it too.

I use plus octane. any other octane makes it worse. Maybe you guys are estimating wrong...the way I calculate mileage is like this:

I hit the trip odometer to 0. Then I drive until its near empty. Then when I fill it up, I divide what I have on the trip odometer by how many gallons it took to fill up.

My prelude gets 25mpg. That I can believe!

AZN, that's how I calculate. my original 2.8 with 185K miles consistently got 34-35mpg highway. I recently built a 2.8 for the car and installed it. I'm getting 29.5mpg consistently. Even on an 800 mile trip this past weekend.

you guys arent going to belive it but its the honest truth. I have an 88 2.5L w/isuzu 5 speed and since usng havoilines gas saving formula I have gotten as high as 40 mpg combined city/highway on rt 9 and 7 from NH through vermont mountains and into albany NY, but I usually average about mid 30's

good to keep your engine tuned up

All around driving average is 23 MPG

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Ed

http://hometown.aol.com/idomy0wnracing

well my 87GT got no more than 20MPG cause of a wiring problem. im hoping the new engine with all new sensors will fix that. but it at one time got as low as 8MPG and filed out plugs in 200-400 miles depending on how hard i ran it.

my 86GT with 4 speed gets 15 in town and about 24 on the highway (i drive hard in town) its got a bad syncro in 4th gear so it grinds going into it. it also idles at 2250RPM until its warm then idles at 1100 RPM it gives no codes whatsoever however the cat was plugged up and i just replaced it so im expecting more improvement on the gas milage. at 65 MPH im doing 3000RPM with the stock 3.65 4 speed which i think is too high for that trans. later this winter ill be putting an isuzu 5 speed in it and expect much lower RPM's and better gas milage.

matthew

Well, the new car has a manual choke and its been so cold I have to use it. I filled it up at lunch and drove 18 miles and 1/4 tank gone...but its a 400hp, 383, automatic

Used to have an '86 Olds Model 98 with either the 3.8 or the 3800(can't remember which ). It got close to 30 mpg highway. The Duke in my 5-speed Indy gets about 13-14 mpg hwy, although after I finish with the new carb it should be a little better...

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'84 Indy 5spd, awaiting wiring harness

quote Originally posted by rogergarrison: Well, the new car has a manual choke and its been so cold I have to use it. I filled it up at lunch and drove 18 miles and 1/4 tank gone...but its a 400hp, 383, automatic

well, you're ahead of me Roger, I've got no choke at all =p

MPG completely right foot adjustable: 15 or so when roddin, up to 20 highway with a carbed 350 mated to an isuzu.

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My Car

I Have a '85 V6 aotomatic with 19,000 original miles and an '86 GT with 84,000 miles.Always log and figure out my mileage.I get a very constant 14.5 mpg city (I commute 6 miles daily roundtrip so the cars barely warmup) and 30 mpg highway.This is getting on the Pa Turnpike a block from my house and going to Carlisle and back.Both cars stock,tuned and in perfect condition.Removed one catalytic converter because I like the sound,no difference.These are REAL MPGs not "about"or "I guess". Wish it was a little better.My wifes Grand Cherokee get 16 around town.

when my car ran great (when i first got it) i got 21-23 MPG, o it's an automatic, right now, i think i have an exhaust maifold leak (tapping noise) the O2 sensor is junk, and my torque converter likes to lock when IT feels like it (usually around 160 or so degrees), i get 16 if i run it hard and on 93 octane, and i can get up to 20 going easy with 87 (yes for some reason i get better mileage on lower octane, i think it might have somthing to do with how my engine is running)
O, and i have a question, if i am turning 2500ish rpms at 60 MPH, what are my gear ratios? thanks.

-Fish

85 gt 2.8 4 speed. 113,000 miles
No cat,14 degrees advance,89 octane with no pinging,K+N filter ,removed water separator,low temp thermostat and switch.
I get a consistent 27 mpg. This includes all types of driving,highway..70-80 mph,around town and running the dragon in second and third gear wide open!!
Before I fixed all the sensors and air leaks I got 16-18.
wheelie

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RED 85 GT MY DEAL'S GAP DRAGON SLAYER
WHEELER'S PERFORMANCE MOTORCYCLE SHOP NEAR DEALS GAP
check out TAILOFTHEDRAGON.COM 318 curves in 11 miles
and now # 2 white 88 gt fastback

my old 88 GT with the 3.4 and the Isuzu tranny got 20ish in town and 27-33 on the highway. When I had the Muncie with 4.10's it got 20 mpg no matter where or what I was doing.
My friend's 88 GT with a 4.9/Getrag gets around 18-20 in town and 25 on the road.

If I had kept my 88, I was going to swap ECM's to a F Body '7730 and enable highway fuel mode. A friend has a V8 Camaro and gets over 35 MPG with highway mode tweaked a little.

'88 bone stock 2.8 automatic. 20-22 all around. Best of 25

88 Formula 3.4 (pushrod) Getrag 5 spd.

City: 18-19 mpg

Highway: 25-26 mpg

Same as the original 2.8. Although, on my first 3.4, I once got 30 mpg. One day I'll dump this sh!tty timing chain and put a new one in. I should get better mileage and stop the pinging.

86 SE 2.8 4spd
Around town I think it's about 20mpg.
Highway is about 28mpg. I haven't calculated this too many times because I don't go on trips very often.
And I think the car is running a bit rich.

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86 SE V6 - daily driven project
87 SE - new project :D

lead footing my 5-speed 2.8

17 mpg

Average driving around town/freeway

20mpg

Driving like a grandma around town and freeway:

25mpg

on I-15 from san diego up on the way to San Fransico i got 32mpg in 5th gear at 2.5k rpms flat open road with cruis control on from fill up to next fill up
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Monkey
"No matter where I go...There's my car"

*Just arrived...84 Indy 4-spd
87 T-Top GT 2.8/5-spd
87 Hardtop GT 2.8/5-spd
97 Trans-AM WS6 6-spd
91 V8 Monster Miata 5spd
69 Mustang Coupe 302 4spd

Added 2 short movies
http://members.cox.net/lothe/monstermovies.html

[This message has been edited by FieroMonkey (edited 12-03-2002).]

Just under 40mpg highway as long as not going too crazy.1984 with a 1995 3100SFI V6 with Izusu 5spd. Even better than it was with the original 4 banger with a 4SPD.

Just did a trip last month of 190 miles+ each way and got 28 mpg. In town and normal driving I get 20 mpg. 1986 2.8 GT

My 4 cyl. got 29 mpg. Thats a combination of highway and city driving. The V8 gets 20 mpg. I don't miss the gas mileage.

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84 V8 Fiero website

About 17 MPG anytime with the damn slush box and a hopped up 2.8. My ol duke with the 5 speed would push 40 easy.

87 gt fiero 10 mpg

84 SE 2M4 AUTO 2.5L
12 city
15 HWY

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Ive Got The Need For Speed

I've actually been getting under 20mpg the last few tanks, but thats city driving in a stck (and I rev high before shifting) and I have to force the car to idle high or it'll stall...but I still can't wait to get my 3800SC installed

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Nick www.naskie18.com AIM: Naskie182010