WW7

One thing I noticed when my 89 was stock, the best gas mileage wasn't at 60-65 mph, if I ran at 70-75 mph my gas mileage improved, this was with 2:59 gears....I believe this was the engines "sweet spot"........WW
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DinoBob

I have 3.07s in my car and get about 17 during regular pleasure driving, which includes some runs to get that nasty carbon out of the chambers. Highway is about 24 on my one long trip (Carlisle and back last year).

GKK

My 91 Vette with 2.59 gear ratio, gets 18.1 Average mpg's...

Not bad since, I installed heavier 19" wheels.

ps374

My computer on my 84 always reads 9.6 which I dont think is totally accurate but I am not getting much better than that with the Xram and inlarged TBS different fuel pump and fuel pressure regulator. I was also told to use 93 Octane since the conversion some 10 years ago. Since I only used this car for pleasure averaging about 1,000 miles a year its no big deal.

QCVette

My mileage is usually mostly highway since I live out of town.

I have had three L98 Corvettes.

My '85 4+3 (0.67 OD) got about 24 or 25 just highway and about 19 or 20 with my mix of roads. (stock except for Borla mufflers.)

My '87 4+3 (0.60 OD) got 30.1 mpg just highway on a 1000 mile trip from Colorado to Illinois. (Calculated from fill ups.) I don't remember daily mix numbers. (stock at that time)

My '88 auto (2.59 axle) got about 28 or 29 just highway and about 20 or 21 with my mix of roads. (stock)

Just a note: My LT1 and LS Corvettes do better if I can keep my foot out of the throttle, but that is hard to do.

Larrye

1985, auto trans, stock rebuilt engine. Averages between 22-24 most of the time, combined highway and in town hopping around.

N42375

My 90 coupe with auto gets 27.5 at 65 mph. 22.2 combination city and country. On a 2500 round trip from Wisconsin to the Smokie Mtns and into N.Carolina, I averaged right at 25 MPG, based on actual fuel purchased. At 55 mph, computer shows 31-32 mpg. Car has 65,000 miles on it with newer Bosch injectors and fresh plugs and wires.

jgalfo

my '86 runs great and has a new tune up and oxygen sensor an I get about 17 to 19 on average. this includes a little bit of spirited driving combined with a mix of country and highway. the on board computer states from 22 to 27 but I am going by what the gas pump reads compared to the miles driven. they have never agreed since I have owned the car.

John

cormorant71

My '87 would get about 20 taking it easy, little less when pushed.

TBSS/85vette

Usually 25+ on the Interstate with my 1985. Right now around town is 19.1

hcbph

86 L98, 3.07 rear with a Tremec 5 speed tranny. Had about a year and got a best of 32 mpg out of it on the drive home after purchasing it in N.M. Running 75 mph at 1800 rpms. I have averaged 28-29 mpg at 65 (about 1600 rpms) and a little less at 55. Most of my driving is cruising so it's primarily highway but the average mpg since maybe April is showing 26.x mpg over the weekend so that's about 1.2-2.5 tanks of gas and I have verified my numbers manually as I've been logging gas purchased since buying the car last August.
Either I'm very lucky or don't drive it as hard as others do, but I'm happy with the mileage I've been getting

gerardvg

How about the actual miles from a full tank ON THE HIGHWAY?

During summer I bypassed my blower and have been running a standard setup, the trip computer will show more miles with a full tank than i can actually get.

I am sure she used to be a hell of a lot better on the highway but i am only getting like 300 miles out of a tank, when she was standard she used to do a whole lot more like 370 miles i thought?

It may be the bosch 111 injectors as i have seen posts on this forum that the ecm to be recalculated for the bosch 3, I have set the adjustable fuel pressure regulator from 50 psi to standard 38psi.

The TPS is set back to 0.54 volts dc from the 0.6 volts dc.
Have reset the trip button and ecm and have done many miles on the highway, the ecm will say 450 miles range but is that just a sales gimmic?

So how many actual miles do you guys get out of a tank on the highway?


(Thanks for reading this, I have an 85).

95 LT5

1989 6-speed
best was 610 per tank

another time got 33.4mpg flat highway with fill up at 1/2 tank.
This was on a gas mileage run.

gerardvg

610 is that km (Metric) not miles?

89 Vett

383 with lots of mods. The computer tells me 16 and change usually, but my calculations put me more in the low 15s. I make no effort whatsoever to maximize my fuel mileage. That's why I have the hybrid.

Balance... right?

hcbph

Gerardvg
I just took a roadtrip the first part of July. 250 miles there, about 50 miles local driving and then 250 back. Trip down was evening, back during the day. Stopped mid trip each way to get something to eat. All highway driving, part of it at 55 mph (about 2/3 of the drive) and the rest at 65 mph, used the cruise as much as possible. Filled up before we left, then filled again when there and finally when got home and it took a total of 20.5 gallons of 10% ethenol blend 87 octane gas for the trip. Just a tad under 27 mpg for the overall trip. Engine is 100% stock as far as I know, rest of the car info above.
Paul

Williamlindsey

My 91 gets avg of 24.6 mpg. best i have done is 29.4 mpg thats doing it the old way calculator miles driven gallons at fill up. worst ive gotten is 21.2 mpg.

PLRX

You TPI guys get some awesome MPGs. I had a 92 Z28 with the 5-speed, and the TPI 5.0L/305 cid engine. That little beast used to give me an average of 32 MPG on the freeway at 70 MPH.

95 LT5

Miles!

MavsAK

worth noting my 22.7 is an Average of city and highway :Cheers:
again...providing I don't enjoy that low to mid range torque tooo much...