I've noticed that if traveling around 70mph the computer readout shows about 32mpg. However, going about 50mph it'll show around 40mpg.
Since my last fill up on Wednesday night, driving very conservatively with 100% around town driving, the readout is still showing 32mpg, which is considerably better than the 25 I was used to.
So essentially, to get really good MPG, drive it like grandma.