AM radio appears to kill auto speakers

The last 5 new cars (Acura, Mercedes, Lexus) have all had to have at least one speaker replaced because of cracking noises after about 2 years. I am not a music fan so I ONLY listen to AM talk radio.  Volume is very typical and not loud at all.  I have a theroy that the limited frequency range of AM radio causes the early death of automotive speakers because they basically aren't excercised enough.

Does anyone have any thoughts on the topic ?