Iam getting really bad gas mileage. My car is a 85 iroc tpi 305 and 3:42 gears, 700r4, Ever sense i have owned it i have only been able to get like 200 miles out of it for a full tank. I thought i could get more then that. It has a new tune up, o2 sensor, new injectors. Even when i had my old 87 camaro with a 355 i could get about that or more. All that had was flat tops, mild cam, edelbrock rpm intake and a edelbrock 1405 carb, head work, and headers. So is there just something wrong or is this how it is supposed to be.
Thank you

 

Milage is subjective to driving habits...i/e if you're in stop and go for the full tank, then you're normal/good....if you run on the highway only at moderate speed, then 200 miles is not good.

 

It is mostly stop and go with the occasional highway drive.

 

Then I'd say you're okay...

I/e my 350 gets close to 25mpg on pure highway driving, in pure stop and go I get around 12mpg.

 

My 85 IROC gets similiar mileage. Highway if I drive it right it gets 23-25, in town 16-18.

 

OK cool thank you very much.

 

There is only one way to calculate gas mileage. Fill your tank up, write down the mileage. Drive till you you fill it up the next time. Subtract the mileage you wrote down at the previous fill up from the mileage at this fill up. Divide that number (mile traveled) by the number of gallons you put in to fill it up. Do it several times and note the type of driving you do between fill ups to determine if it is consistent or not. I stopped using Chevron Supreme from the local station after doing this and finding out my mpg varied from 17 to 21 for the same type of driving (back and forth to work). With anyone of 2 or 3 other gas types at local stations I get a consitent 20 to 21 mpg. Not sure, but I suspect the Chevron was not always 93 octane in spite of what the pump was labeled. By the way, with a load of "stuff" for the weekend, my wife and a speed of 70 to 80 mph I get 23 on highway trips.

 

I have something weird going on. (Other than my car is TBI.)

6-10 city
20+ on the highway while doing 80-100.

Check sig for parts.

 

i save gas by driving like grany and keep the rpm below 2.5K, sometime i shift from 1-3-5 it help