I just pulled my 1992 3.1L Camaro out of the garage and dtove it back to school last night. The car has sat at my house for two to three years with my dad getting it out about once a month to keep it running. The cars has 229,880 miles on the original engine and the 700R4 transmission was rebuilt at 212,000 with a mild shift kit and a corvette shift servo. I filled the car up with gas before i left and last night when i got here i topped it back off. It was a 174 mile trip and the car got 28-30 mpg on the way. The trip was mostly interstate with about 40 miles of 55 mph highway. Is this a normal mpg for the car or is it a little high. I just haven't drivine the car in a while and it getting almost the same mpg as my girlfriends accord.

wow....i get 22 IF IM LUCKY. I know my motor isnt 100% perfect but its not that bad, i mean the thing is far from a junker. I just ordered new injectors cause i know a few are leaking(leak down test). Hopefully after the injectors ill get 25 or so. If i race around all the time i usually see 17 or 18. Just be glad your getting that kind of mileage. IM sure alot of people on here will tell you they wish they got that good of gas mileage.

Yeah, i was actually in shock when i did the calculations. The only thing that different now than when i was driving it before is i changed from "dino' penzoil to penzoil platinum the last time i changed the oil.

Go to Fuel economy.gov. Those numbers are usually pretty accurate. Here is the link for yours.
http://www.fueleconomy.gov/feg/sbs.htm

I use to get those number listed on the website consistantly. I've recently replaced the thermostat, put the TPI air box on it, and the the throttle body bypass, along with the switch to synthetic oil. My car was a;so optioned from the factory with a 3.08 rear end gear.

the highest i've seen was 33mpg. i've got oversized rear tires though, and i was only running 1800rpm at 75mph

at got 407.5 to a empty tank well almost empty I went up a hill and the car start to cut out so about 27 to a gallon not all highway miles. this all in a weeks time

28-30mpg highway is fairly accurate for a stock (well maintained) car. I used to get that routinely with my '91 along with 17-18mpg city. I say I used to get that because I am currently in the process of tuning the computer to match my other modifications. However, with an unfinished tune I'm now pulling off 21mpg city routinely while beating on the car. I can't wait to finish the tune and take it out on the highway to see how it does. Lean cruse FTW!

After prolly two years of headaches in the gas mileage area, I finally got two full tanks in at 27mpg, half of which was city driving. So yeah, I'd completely believe your numbers and wouldn't doubt that one could get up to 35-38mpg with a steady foot and a lot of routine maint... only on the interstate that is.

i drove it on a 3 hour trip and got 31 mpg, and then i just drove it on a 2 hour trip and i got 33 with no mods other than a K&N Air Filter, so I'm pretty happy with it, its a great engine

if i drive normal i can avg about 32mpg even with the 4:10 rear gears and high stall converter with no lockup

at the same time i can get that way down to liek 10-12 mpg if i drive with a heavy foot

i get about 23 around town in the 92. I havent done any long highway runs to see what i get there.

Sry to rob this post but i have a quick question for you project....i lost my chart so i cant tell but what rpm does your car sit at on the highway with the 4:10...i was looking at doing 4:10 but was scared the rpm might be too high...i drive 45mins at 80 to get to the lake house about once a week so i need to be concious of my rpm lol....you said you dont have a lockup tho so the results will be way off...oh well let me know anyway

on to the gas mileage deal....i believe its possible to make 32 with these cars...ive seen another 91 firebird(not mine) do 33 on the highway...at the same time if you drive it hard it will only make 17 or so...personally i think that is the perfect set up cause you can make great gas mileage but yet when your going full out all the time your still beating trucks mpg....**** my 06 dodge 1500 slt makes 17 daily and thats driving it half way nicely....i personally am a spirted driver weather im on a lawnmower, my firebird, ma's hybrid civic(50mpg in the city!), or my truck...so pretty much me saying i get 22 average per week is probably not its full potential...i have a bad habbit of liking acceleration and taking corners fast in the firebird.

dang i have a gas guzzling V6 then haha, i only get 250 miles per tank so thats like 17 mpg, how are you guys getting in the 20's???

My car is horrible compared to the rest of them. I did the full tune-up and I still get 14city and 22highway. I guess its just the carb/17yr old driver combo that equals bad gas milage though. Anyone know what a carbed v6 should be getting?

keep your foot out of it and see what kind of milage you get.

a good tuneup wouldnt hurt either.

its pretty tuned up, i have new plugs, wires, ignition module, coil, new tranny not too long ago, i just replaced my timing chain and got new valve cover gaskets and i got new exhaust manifold bolts, so i dont have anymore leaks, yeah i should try to keep my foot out of it......but its so funn hahaha

Like everyone is saying: tune up, regular/general maintenance, dyno tune, and keep dead weight out of the car. Also tools not needed take out, maybe find a aluminum spare if you even want to keep a spare tire and scissor jack instead of floor jack. <-- My wife did that before instead of asking where the scissor jack was.

Last thing we should beable to atleast get 25mpg my brother-in-law
knocks off 24-26mpg in a 2004 v6 auto tacoma 4dr with those bigger a/t tires

I drove from San Antonio, TX to Tampa, FL(1200miles) and averaged 29-30mpg. I was moving so I had my car full of whatever I could fit, it made the car squat just a little which it doesn't even do that when 2 people sit in it. I'd say that's pretty good for a car hauling some extra weight.

so im thinkin the only thing that could be making my gas mileage bad is my new injectors, they are meant for a 305, would they really make that big of a difference?

Possibly.

its been a few months since i drove my car but its not bad at all with the 4:10's

but an easy way to figure it out is this

if u have a 2.8 car u have 3:42 gears and 4:10's would make it about 7rpms higher then it is now

i belive the 3.1 cars got 3:23's??? and if so 4:10's would make it about 900 rpms higher

the 4:10's may hurt a lil bit of highway mpg but they actually improve the city mpg due to not having to step on it so hard to get the car moving

Your observation of 30 MPG is pretty similar to my experiences with my own car. I used to drive from my home to college. It was just over 150 miles, and 90% of it was interstate. I would top the car off at the gas station 1 mile from my house, reset the trip odometer, and then drive back to school. When I got off of the interstate, I would top it off again and then figure up the mileage. I did this about once a month, and usually it was somewhere between 30 and 31 MPG, with the cruise set on 77 mph.

My car is a 1992 3.1 automatic. I imagine that a 5 speed car would get about 33 MPG doing the same thing.