i counted again last evening and this morning for a total of 6 sets of data:

morning commute #1: 5 cars + 1 motorcycle
morning commute #2: 6 cars
morning commute #3: 4 cars

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


so now with 3 full days of commuting data at hand, i feel confident enough to calculate a real average:

on average, i am passed by 4.67 motor vehicles per commute leg (5 miles).

let's just round that up to 5, and because my commute is 5 miles long, we can call that an average of ~1 passing motor vehicle per mile (1 pmvpm)

and i promise i'll stop doing this now