The first one I spotted was nothing more than a bumper and tail lights in a driveway; I had to wait until I passed the house again to get a better look. Eventually I ended up getting off the bus in order to get better pictures.
While passing the Cambridge fire station just outside the Harvard Square "tunnel," I spotted something orange-ish in the parking lot:
I was pretty disappointed that I couldn't get a better shot, but I was sitting by the aisle, not the window, so I was lucky I got this. I thought it was an Oldsmobile Cutlass Supreme convertible until I took a closer look at the bumper and marker light, and realized it's a Buick Skylark convertible, with some sweet vintage Keystone wheels that might go back to when this car was new.
I looked for the Buick most every day I passed the fire station on the way home, but I never saw it again. The Lincoln was around for a while, but was gone by mid-September. The Dart is still in the same place.