Why does my 2007 Honda Civic use so much gas?

I bought this car from my dad, it has 135,000 miles, and it is guzzling gas. I went through a quarter of a tank by just driving around town when my dad uses much less than that to drive to work and back which is about 100 miles. It is well maintained, and i just don't know the problem. Do people still do tune ups, maybe that is what i need. I'm not sure someone please give me suggestions.

How long have you been driving it?

Before you determine it's "guzzling gas" you should go through at least 2 full tanks to get an understanding on how much it's actually using… And "driving around town' could mean a lot. If it's a lot of starting/stopping, stop-and-go traffic, etc… You will burn more gas.

Figure out your ACTUAL MPG, by filling up, writing down the milage and gallons, then fill up again, and figure out gas and milage. If your MPG truly is out of whack bring it to a mechanic.

Definitely do what Mike above me said. I do this every time I fill up. You will see your average MPG for that tank of gas. Then if you see one tank of gas that has an MPG totally different then what you usually get, then you know there maybe something wrong with the car.

Read this, this may help:

http://www.8thcivic.com/forums/garage/264683-tracking-my-mpg-my-2007-honda-civic-ex.html