If it is the cars around you the only way to eliminate it is to disconnect the antenna, alas, that is counter productive (or drive where there are no cars around you.... Many folks in this group... Do just that)
I recall a Science Fiction book where a Human was in a planet where a war was being fought, The Enemy had a completly silent plane they were using to bomb and straff the "Good guys".. You see, they communicated by Antenna, not ears & mouth, the engine on the plane was a diesel, no spark, no EM noise. The human, could hear it miles away