On the D3 you can hit the screen and it says something like calculate a radius detour from this point, (with a list of ranges). I find this to be the most useful option for myself. My wife just got a Explorer with Sync and its Navigation does NOT have it and I'm surprised since it seems like such an obvious feature.
So I just want to make sure the F series still has it. Can you do it via voice commands, (like "calculate 1km detour" ??)