Some time ago we wrote an article about dangerous levels of EMFs in some hybrid cars. A little more research shows that modern petrol / diesel vehicles can be even worse in some cases.

The problems are:

1. You are in a metal box , which traps electrical fields within it.
2. The alternator is the equivalent of a sizeable motor generating significant EMFs .... Read more here: https://www.lifeenergysolutions.com/blog/emf-in-cars/