I have a 97 EX automatic with 86000 miles that gets 20 mpg in town at best. I purchased it two years ago with 78000 miles. I have done the following:

Timing belt & tensioner
water pump
cam and crank seals
valve adjustment
Front/Header O2 sensor
Distributor cap & rotor
Plugs and wires
Trans fluid flush
Fuel filter
The car starts and runs great. The transmission shifts smoothly up and down gears with the exception of some slipping when engaging D-rive to take off. I does have a pronounced whine in Reverse but I think thats normal.

It appears the auto trans may have been swapped earlier in life as there are hand painted / non factory numbers on the trans case in ink which may indicate a rebuild ?
I know an EX will suck gas / VTEC but I know I should have better mpg and I'm wondering if it's worth the cost to have diagnostics done on the trans ? Or maybe a Cat/Conv check ? My next part swap will be the rear O2 sensor.
All thoughts appreciated
CH

 

20 mpg city is kinda low for a civic. is your air filter dirty at all? are you using the recomended weight of oil? check spark plugs? is your idle in normal positions when idling? i dont knwo im just throwing stuff out there that maybe you should check, sorry i cant be of much help

 

I have a 1996 LX with a automatic and was bitching about getting 29-30 with the A/C on. Now I am pushing 32 with out the A/C on. Sounds like you have covered the parts that needed changing. Take it to a good muffler shop and get them to test the cat/conv. My bro had a Subaru that was only getting 21-22 mpg. Took it to a muffler shop and they found the cat/conv was bad. He is now getting 28 -30. When it got hot the stuff in the cat/conv plugged up the guy at the muffler shop said.
If it is like my 96' the cat/conv is made to the exhaust manifold and they cost 250 to 300 hundred bucks ! If you do need one and do not have to pass a smog test were you live there are headers on eBay fo 80.00 buck shipped to your house ! If you have to replace the cat/conv and have to pass smog test and can not use a header let me know I live in Tn. and do not have to pass smog and am going to put a set of headers on mine 96' 1.6 and the car only has 29,000 miles on it no **** 29,000 on a 96' ! So drop me a email if you want to buy my low mileage cat/conv.
I am not putting the header on to hot rod I am cheep and want to get every mpg out of the car I can. Plus the extra 12-15 HP would not hurt too. Also are your tires aired up good low air pressure in tires can drag your mpg down too