i counted again last evening and this morning for a total of 4 sets of data:

morning commute #1: 5 cars + 1 motorcycle
morning commute #2: 6 cars

evening commute #1: 3 cars
evening commute #2: 7 cars + 1 motorcycle


so ~6 passing motor vehicles is average for me over the course of 5 miles.

man i love mellow side-street bike commuting!