[tenebrisalietum]

I think it's more the legal notion of intent that separates manslaughter versus murder. I would venture to say most car crashes that aren't attacks are not intentional, therefore they are accidental. Also if you experience a fatal accident in a car, it's likely enough to be a crash - so I would also venture to say most people understand "car accident" to strongly imply "crash".

[bookofjoe]

Ah, therein lies the rub: implying something softens the unconscious blow. Much science underlies meaning.