I have to differ with that but at the same time, you're no dweeb. When I get home in 2 weeks I'll run a ditch test.
For example, take my current tour.
I have 165 kills in fighter mode. 3 "ditch" and 8 "death".
If the ditch would count as death too, I would have a k/d of 165/(3+8+1) = 13.75
But actually my K/D is shown to be 18.33 - wich is exactly 165/(8+1).
So you see, the ditches didn't count as deaths for k/d computation.
And this is the formula from the official HTC help pages:
Kills per Death = TotalKills / ((Discos * 0.5) + Bails + Captures + Deaths + 1)