Rep Power: 0

My 1998 Civic seems to be getting very bad mileage, at least for the make/model. My wife drives roughly 100 miles every day for work and 95 of those miles are expressway. She's been getting about 24-26mpg. The car was a hand-me-down from my aunt that bought it new. It had 120k on it when I got it and a great majority of those miles were in the city. The only driving issue I've noticed is that from a stand still, it throws you into your seat if you're don't very carefully touch the gas. It is an automatic. It's been maintained regularly. I was told it had a complete tune-up right before I got it and from the look of the plug wires and fuel filter, I would say that is accurate. I'm going to switch the plugs to some NGKs that I picked up today, even thought the plugs are also likely new. Does anyone have any ideas?

 
Rep Power: 518

Air up the tires.
Get rid of dead weight.
Make sure brakes aren't dragging.
Drive it like grandma would.
Winter blend fuels make you lose gas mileage.
Cheapass fuel costs you gas mileage.
Ethanol in the fuel costs you gas mileage.

Read up: http://www.toptiergas.com/

Edit: If the plugs already in it are the correct NGK, leave them alone. Save yours for 30k from now.

 
Rep Power: 0

Well, I think the tires are fine (they only have 3k on them) and I check the air pretty regularly. There is no excess weight in the car. My wife drives alone. We only fuel up at Shell, which I believe is TopTier. I'll check the whole brake thing, but I think I would have noticed an issue there. She drives 65 on the expressway (the limit) just to save on the gas, so she's already driving like granny. Thanks for the response.

 
Rep Power: 518

http://www.fueleconomy.gov/

My new Civic is rated at like 39 highway. I got 37 something at 70-75, and have seen as much as 52.3 at 45-55mph on a 45 mile run.