C4 mpg help

[Dirtfarmer]

Need a little help here. I've been searching the forums for C4 gas mileage and have seen 15 to 33 mpg depending on driving style, etc. Does anyone know what type of mileage to expect from a stock '90 automatic coupe, driven calmly (most of the time, let's be real here ) back and forth to work?

Fuel is getting too expensive, hopefully I've found the solution to my high fuel costs.

 

[LT4man]

The EPA ratings for the 1990 L98 coupe w/automatic are as follows:

16 city - 24 highway

These are estimates. Your mileage will depend on your driving habits.

SAVE THE WAVE!

 

[Dirtfarmer]

Thanks a lot for the info.

 

[ON 7TH]

16.3 ON MY 90
19.5 ON MY 85
NOT MUCH MY 78

 

[89sleeper]

I have 2 89s both are 6 speeds my coupe has a built 383 it gets just over 23 mpg with 3;54 gears
My roadster is all bone stock with 3;33 gears it gets 30 mpg
(they both get their best mileage in 6th gear at around 70mph with cruise control on and the tach is turning around 1700 rpms)

 

[3dale1]

I average about 24 MPG highway and +/-20 overall. Never thought I'd say it but I'm getting envious of the guys with 2.59's.

Car is a stock L-98 auto. with 3.07's and a good exhaust; no codes, runs AOK.....what do I have to do to get up there with the 30 MPG guys?

 

[c4cruiser]

Of course the type of driving and traffic has a lot to do with fuel mileage. What sort of roads do you travel to work and back?? Freeway, city streets? mix? Lots of stop and go driving?

My 87 coupe (4+3 3.07 gears and some mild mods) will get around 16.5 around town where the roads are a mix of city traffic and boulevards. Speeds run from the typical 25MPH city streets to 40-45MPH boulevards. I try to use the OD as much as possible to keep RPMS low and let the torque do the work. I have found that 3rd gear/OD is a lower RPm than 4th/no OD and it seems to get a bit better mileage.

For freeway cruising, I try to set the cruise control wherever possible and I have seen 27MPG (caculated on paper) on 100+ mile trips.

My 92 vert (LT1, A4 and 2.73 gears) did much better on the freeway with my best being 32.4 at a cruise-control set speed of 83! But the LT1 didn't have the low-end grunt that the L98 does so in-town mileage was not much more than 16.

Like any other car, make sure everything is in good condition; clean air filter, good plugs, new dist cap/rotor and wires in good shape. Tires should be inflated to recommended pressures (you can go to 35psi) and limit the use of the A/C when possible. I have tried using the mid-grade (89 octane) fuel in my 87 but it did have some ping under mild acceleration. Never checked for a difference in mileage as I decided that the ping could very well cause engine damage if I drove the car hard.

 

[scotch1]

My stock, 1990, six sped , coupe L98, gets 19, around town , and 25 on the highway, not bad ..but depends on type of traffic, and driving, I do.
Tom

 

[G Winter]

My 90 with six speed gets 20 to 24 all around, most of the time about 23. I live in a small town and drive mostly 2 lane roads, short jumps of about 15 miles.

Glenn

 

[Dirtfarmer]

Thanks for all of the responses.

We're going to look at a car in the morning. '90 automatic coupe, red on black leather, 70,000 miles. New injectors and tires and a recent tune-up. From talking to the guy, sounds like a nice car. We'll see what it looks like in the morning.

 

[SPANISHVETTS]

Thunder does 26 MPG on the hi-way if I keep it below 100 MPH. In town 15 MPG is tops.
A while back I was forced to do a 300 mile trip at 80 MPH. Thunder did 29 MPG and we could hear the stereo.:crazy

 

[Vettefan87]

Car is a stock L-98 auto. with 3.07's and a good exhaust; no codes, runs AOK.....what do I have to do to get up there with the 30 MPG guys?

When is the last time it had a tune up? Might want to try there with a new coil, cap, rotor, wires plugs. You could also try to clean out the throttle body and replace, or clean the air filter depending on if it is a K&N or not.

 

[3dale1]

Yeah, you're right. Plugs new, throttle body cleaned, new AF this winter. But I have not changed out any distributor parts.

Bought the car March '05 and have done alot of PM since. For the cost, I should do this. Maybe new O2 sensor as well now that I'm thinking about it.

Appreciate the input! Joe

 

[Edgar]

According to the display on my '93 I average 16.4 but most of my driving is city. On the road trips I've taken I usually get 24-25 mpg although the display the other day said 99 mpg...down hill, in a tail wind, foot off the gas...

 

[paulmeisterpk]

I mostly notice 24 to 25 mpg doing mostly open road driving. Sometimes up to 27 if I'm really babying the '85.

 

[Dirtfarmer]

Thanks for all of the responses.

We're going to look at a car in the morning. '90 automatic coupe, red on black leather, 70,000 miles. New injectors and tires and a recent tune-up. From talking to the guy, sounds like a nice car. We'll see what it looks like in the morning.

Went to look at the Corvette, needed a little work but all in all a very nice car. Long story short; went to look at a Corvette, came home with a 2006 Malibu. :L

Thanks again for all of the input.

 

[thirdtimevetteowner]

No offense to any of you guys concerned about mileage, especially w/the escalating prices, but after all it IS a Corvette. I'd swap the pig-a$$'ed 2.59 gears in my '89 for 3.73's in a Heartbeat (pun intended), just so it would get out of it's own shadow. Whoever heard of 3.08's being the "performance" gears behund the stick shifts, especially the 4 + 3 trannies? It's the 700R4's that need the help. After all, the ratio drops virtually in half when shifting to 2nd gear, which is why most drag racers short-shift it there, to keep it more within the peak torque range. However if I had a D44 (putting D36's in a Corvette is another sore spot altogether) with even 3.45's, or 3.54's, then adding a Mini-ram, Lt1 converted manifold, Holley StealthRam, or whatever else there is out there to get this thing to spin to a respectable 6000, I wouldn't need to short shift and would cut a second off my 1/4 mile times.
Oh well. That's just my 2 cents worth that I had to get off my chest. Happy motoring. BTW, has anyone besides me thought of boycotting Exxon one month, BP the next, then Citgo and so on and so on? If only us Americans could stick together instead of complaining, maybe the oil companies would get the message. While I'm at it, why not vote ALL of the incubents out each term to get some new blood in there and get the existing fat cats w/their 3 martini lunches, free cars, free gas and paid mileage to drive the free car w/free gas, out into the workforce so they can feel what it's like to have to PAY for the things we NEED for everyday living, like gasoline?!

Rich K