I'd say I have the same issue too.
As the nature of the radio signal reception mandates,
it is not an ON/OFF problem.
it has no symptoms where/when signal is high. (in the city)
But when you go away from signal source (where my work happens to be)
it starts parasite sounds as the signal power drops.
Weather conditions also play a minor role too.
But as a comparison, I got wife's Merc for a few days and
it had no reception problems on way to work.
But man, the way it goes when you kick the pedal !
And then there are MP3s, CDs