VLF earth-mode experiments

Back in 2013 I tried an experiment to see where my VLF earth-mode signal could be received in the car. 

My TX was 5W into my grounded electrodes. On RX, I dragged a resonant loop behind the car receiving on a PC.  The earth-mode signal popped up at odd points many kilometres away.. 

Since my September 2013 stroke I have been unable to do field work.