I see plenty of erroneous results near me (45 mph up a hill? For real?) that appear to be in the middle of another ride, so I'm tempted to believe they drove a car for that segment but it's not probable. I think Strava has some assumptions built in that you can hack if you're that interested in getting a KOM.
Check this segment out -
http://app.strava.com/segments/965049
There is NO EFFING WAY anybody is making it up that hill at 35 mph and the start point is already on a hill, so it's not like you come bombing off a downhill. I recognize some of the names starting at #2 (because they feature prominently on a lot of the segments I ride, and usually well above me
)
If you look at the rest of his ride, it's a perfectly normal looking ride though -
http://app.strava.com/rides/6010202#
So Strava apparently has plenty of bugs left to work out. I rode a segment last week and probably averaged about 22-23 (which is obvious looking at my speed chart) mph but my overall average shows up at 28 mph. Obviously wrong.