31 mpg is not bad at all for the 2.4L.
We just got back from a long road trip to St. louis in our 08 corolla CE w/ the 5 speed.
The first 2 tanks going 75 mph we got 40 mpg. Wish it would have stayed that good, but once we got ahold of that $hitty gas in Nebraska it dropped like a rock. But we also zipped thru that state at about 90 mph to though.
Made some good time on the way home, and we saved $800 over buying airline tickets.
