Driving away from my house, I encountered my neighbor from across the street as he returned home, and he spoke. That is, he raised his hand from the steering wheel in a slight wave.
In eastern Kentucky as I was growing up, to speak (vi) meant to acknowledge an acquaintance in passing, without uttering words: “I saw John Early on the street yesterday, and he didn’t speak.” Not acknowledging someone in this way was a minor affront.
Speaking, in this sense, is performed in motor vehicles by raising the fingers of one hand casually from the steering wheel. In a rural area like Fleming County, Kentucky, where everyone in theory knew everyone else, some drivers would “speak” to every driver they encountered so as not to risk giving offense.
I offer this word, without charge, to the Oxford English Dictionary, which does not yet record this sense — though perhaps the dialect specialists may have gotten hold of it.