I remember having it set on a 60 road that was really hilly (short steep rise and fall) and having the car slow to about 55km then kick back to 3rd (sometimes second!!) and rocket to about 62 or so at the apex and then roll to about 75 - 80 down the other side.
Deffinately an occasion where you should keep the tranny in 3rd and use your right foot.
How many of you with 4sp auto lock it in 3rd for the above occasions and for heavy traffic, stop start etc? i do it all the time, especially when its less than 60-70 km/h. Saves tranny where, fuel and more pleasant than the frequent kick down.