I've been running an average of about 470-500 miles a tank, no real difference if I'm getting on it, or just driving easy. Works out to around 30mpg give or take. I track it every fill up using the trip odometer, and how ever much the pump says I use.
Nothing special done to it, K&N filter, Mobil Clean 5000 oil, and I seafoam it every 10k miles, Pennzoil Syncromesh in the tranny. (99, 5 speed sedan, ULEV)