so i have a 93 si hatchback, and although it has new plugs and a brand new air filter... on my last tank i drove 330 miles most of which are highway and averaged 40.5 mpg when i got back to town and checked my mileage...

I mean i do drive very conservitavely... and i'm in nuetral a lot because i anticipate lights and whatnot... but 40 seems pretty high to me, and i know that i have the D16Z6 in there...
i'm just wondering what anyone else is getting according to what the EPA estimates for their vehicles are

 

bump...
it's almost off the first page

 

Are you sure you did the math right? You would have had to be around 3/4 of a tank before you filled up with those numbers... I haven't even come close to those numbers in my '00 EX... I'm around 31-32 with mixed driving no a/c... 27 with a/c (and a bad compressor clutch bearing... adding more mileage/power loss)

This is what EPA (fueleconomy.gov) says...

 

well that epa rating is adjusted for fasdter driving (80 and up mph) and the use of a/c

my car needs an alignment and starts shaking at like 72-73... so i was going like 65 to 70 miles an hour the whole time with nothing but my radio on... my tires were at like 36 psi

i definately did the math right, i check my mileage every single tank and the worst tank i've had with my civic was the majority of city driving and i used the a/c because it was a heat wave... and i still averaged 32 on that tank, i mean every single tank i've done with this car has been 35-37 with an even mix of city and highway, so i guess mostly highway @ 40would make sense compared to all those numbers

 

Since you check your mileage every single tank, show us your logfile. I have posted mine here several times.

Somehow I cannot see the EPA rating gas mileage at "80 MPH and up". Would you post a link to that info please?