Using a Trifield 100xe Gaussmeter, I'm getting 15-25 mG at driver's head location at highway speeds. What is the major source of the EMF in the cabin and what is best strategy to reduce with shielding material?

This is a 2006 Honda Pilot.

 

Are you trying to block cancer or do you have electronics that require better shielding?
Best way is to shield everything out but thats nearly impossible unless you re-do the whole cars entire wiring or use lead as a shield for all body panels.

 

i'm a little surprised you found this forum and posted in it before finding this link below...

car radiation protection

this may be more cost effective- personal protection

 

ROFL, scientific studies have shown that EMF radiation from cars does not directly correlate to cancer. Now having a power plant or a substation nearby may be a different story especially with the high energy buzz you hear.