So what are the fastest one-liners we can share in these conversations? Since altercations leave one wishing they had thought of just the right thing at the time, it's good to practice. Maybe these:
"Weightwatchers is right over there"
"Have another twinky and relax"
"Krishna loves you"
"Jesus walked" (if they have that holyer than thou, progress-hating vibe working)
"Thanks for sharing"
"Well one of us has to think of the environment"
I pedaled out to my mother's birthday party, and my sister got into a bit about how the cyclists in her area get in the lane, then they go slow, and you can't go as slow as they go, etc... So I asked why someone in an air conditioned environment with entertaining music and sometimes even a dvd player can't actually slow down for a sec. The thought never occurred to her.

Just chat with the Onstar gal until the pesky cyclist moves for pete's sake.