Should I use overdrive in my car?

I want to start driving more green, and save on gasoline. I live in Very flat south Louisiana. Almost all of my driving takes place in the city, with lots of signal lights and stop signs. My average speed is between 30–35 mph. So here’s what I’m wondering: would I save gas if I turn off the overdrive on these daily commutes? Not sure if it matters, but I drive a 2007 Nisssan Versa 4 cylinder.