I get WSPY at home on my receiver (Drake R8) and loop antenna with weak signal. Hearing it in the car (also Equinox) is a different story. It's there, but I also get splash over from WPNA. I am surprised that FCC has been granting them the STA all these years. It was first granted back in 2002 and renewed as recently as July 2019. According to their application they are using a long wire antenna with 125 watts of power. The other interesting thing is the Batavia SDR, which I suspect is operated by the same person that runs WSPY. The WSPY signal on that SDR is very strong, while other local stations are much weaker, including the big 50kW blowtorches. The link to that SDR is http://w9xa.us:8073/
If I'm not mistaken the stick....er, "the wire"...is on the south end of Geneva, which is adjacent to Batavia. That makes sense because where the signal began to deteriorate on the car radio was on Geneva's north side. Thanks also for the info and the SDR link. I'll check it out. And finally, your theory about the connection between the owner of the SDR also being the person in charge of WSPY seems plausible.