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Did you even read or understand my post?
What I was trying to get across is that normal road bumps can easily exceed the stresses capable from even the most obnoxious stereo system.
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Absolutely not.
A normal automobile travelling any road it's actually capable of driving on will have large amounts of subsonic noise generated. We don't hear that low but do feel such noise through our bodies skin, bones, and via atmospheric pressure senses, some of which are in the ear canal (also the eyes; we have no nerves in our eyes so no pain but that doesn't mean the brain doesn't notice).
However anyone who has ever put a Sound Pressure meter in a moving vehicle will tell you that "large amounts" does not mean even long term hearing damage levels around 90 dB or a bit higher. More like 60 dB, perfectly safe for anyone to experience for extremely long term continuous exposure. Like years, and nobody lives in their vehicle like that (we park them sometimes).
A high powered car stereo, even just rather ordinary examples, will be capable of SPLs at both audible and subsonic frequencies well above 90dB, some up to short-term damage levels (above 105dB) and beyond, while "Competition Level" systems have been known to exceed 140dB by significant margins (exposure limits measured in minutes, not hours).
Now, if you are referring to mechanical stresses (bending, heat generation, stress cracking) in the vehicle suspension and body, they are (obviously) large but that's what suspensions are for and the OEM designs suspensions to handle the expected loads and stresses. That is going to be less than the pressure stresses within the cabin (windows, door and trunk seals, etc) from low frequency audio systems operated at high level.
