avg speed is (on the two different computers I've used) is current speed devided by time and calculated every few seconds (5ish). It is also just moving time - mine pauses when I stop.

To get an accurate gauge of what your cruising is wouldn't you want to find a large flat parking lot and ride in a circle for 30 minutes? Do that for several weeks at the same time and then avg those out to get your avg spd? Boring as L? You betcha, but wouldn't that get the most accurate data you are seeking/trying to figure out?