I have a 90 RS with a stock 305 TBI and a 2.75 open dif. I am only geting 15 MPG city and 18 on the highway if I am lucky. I repalace the O2 not long ago and that did not do much. the car does not have many miles for the age only 84,000. Gas in chicago suburbs is around $1.70 a gallon for the cheep stuff. Is this right or should it be better. If this is bad. where do i start.

 

Tune it up. Plugs, cap, wires, timing, run rich?...good mods for mpg: open element, headers, exhaust.

I can get up to 26mpg city driving with a well tuned car, I average 22-23 normal driving (quarter to less throttle). I seem to be the exception on mpg, most get 18-19 city. Highway varies, I haven't tested my car out on it yet but I would imagine up to 32-34mpg at 70mph, it most often ranges between 24-30.

Depending on how you drive effects your mileage. Hammer down, half throttle, quarter, hardly touch gas?

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1989 Camaro Convertible RS
dark silver w/black top
305tbi, auto, 2.73 posi
SLP exhaust, 16x8 black GTA rims as soon as I get them
Check out Phil's Rice Boy Page

 

I consistantly get 21 to 22 mpg on mostly highway driving. You might check your cat it could be stopped up or close to it. A lot also depends on how you drive too. Do a tune up on it with new plugs, plug wires, dist cap and air filter. This should help as well.

Steve

 

Didn't think of the cat, good idea steve...that robs enough power and flow as it is. remove or replace that too for some mpg.

 

i was getting sh*tty gas like 10-13 miles to the gallon city driving.. my fuel pump went bad and now i am up to 20-23 $298 and better gas mileage cant complain!just thought i would share more story
Shawn