So many good posts to respond to -
Good point about how long the rag had been in the tail pipe... too late now to analyze, maybe not.... would have to check how much exhaust soot had build up on it... In fact if the rag were really clean would show it placed in pipe after car had be turned off...
The rag - was it simply placed my MM as a warning after car crashed? Was it visible if that's the case?
Using the rag to disable the car after it had stopped at the gas station by some seedy character... problems with that. Perp would have to have found it in the kit Fred had packed for her... Also, why do that, not knowing how far or where her car would stop. Simply following her car to remote spot and bumping into it or cutting off seems more likely. No signs of that.
In Renner's blog, he said that the rag was stuffed way up into the tailpipe, so I changed my mind about the rag as a flag. Renner got the info from the guy who had Maura's car in his lot. I'm almost convinced that the rag was there for a while. There was just enough air coming through that her car didn't stall. She could have had an exhaust leak in the pipe or there were some spaces around the rag that allowed some air to come through, but her car's performance was probably noticably lousy. Maybe someone at Amherst did it as a joke or wanted to cause her trouble. I had my car keyed a couple of times in a college area. Someone was either upset with me or they were just being jerks. I have a feeling they were upset with me and it was someone I knew.
I wonder if LE actually showed Fred the rag or did Fred assume it was from
his emergency kit. I think this detail is important. I'm almost convinced that the rag in the tailpipe was the reason her car's performance was bad in the first place.