'02 Civic mileage and transmission

Recently purchased a used '02 Civic w/auto transmission and 58,755 miles. I have installed new plugs, air cleaner, and fuel injector cleaner. Only once has it done better than 30 mpg and only barely. I’m not a race driver. The only unusual characteristic is that when cold it shifts slowly and at higher rpm from 1st to second and from second to 3rd. After it’s warm, shifting seems normal. Any suggestions as to the next step to improve mileage would be appreciated.

Your gas mileage (30mpg) for daily suburban driving is not unusual. However, any unusual behavior by the transmission spells trouble, and I would get it into a good transmission shop right away!