22.74 mpg average with an m6 3.42s CC306, ported heads, full bolts ons, etc. All highway for 1101 miles, average speed probably 80 mph.

 

You settin the cruise at 90mph? lol

 

i dont use cruise lol i always run at 80

 

80 might be why...the mpg is based on a 60mph cruise

 

with my 94 with LT's and ORY hooker aerochamber m6 with stock gears i usually get about 27 mpg on the highway setting the cruise at 75-80 and about 29 with the speed closer to 65-70 in town i usually get around 20 mpg

 

Avg. 22 city/mostly highway cruise about 75-80 mph

 

Heck with my motor I will get 15mpg pounding on it around town, and the last 'freeway' trip was 19.5mpg and that included 8 passes/burnouts at the 1/4 mile dragstrip.

How do you calculate your gas mileage? The best method is to reset your trip odometer when you fill up (top it off) drive until you are near empty, then top it off again and take the miles on your trip odometer and devide by the gallons you put into the tank.

 

15 city
19 mixed
26ish highway

'97 Z28 M6 3.42 117k mi
stock opti, stock fuel pump

 

i used to get 20/gallon average, and i absolutely beat the **** out of the car everytime i drove it, something is up with yours

 

19 to 24 depending on how many passes at the strip.
23 avg. highway.
3.42 gears

 

thats how i calculate it i get 180 per tank and i have a 15.5 gallon gas tank

 

Thats part of your problem right there, use the previously mentioned method to figure it out and your numbers will be alot more accurate. There is no way you are bone dry every time you fill up, otherwise your pump would have bitten the dust a long time ago.

 

I get ~14 mpg in the city and ~25 on the highway. That's with an M6 and 3.73's. I haven't checked it out since the LT install, so those numbers before are just with CAI.

 

I get 12-13 beating on it in the city and it runs really rich and needs a better tune.

 

Sounds like half you drive like grandmas