I was a Test Engineer at an aerospace electronics company for 17 years. Part of my job was to do vibration testing on electronics systems we sold to the government. I can tell you first hand that even low levels of vibration over sustained periods will shorten the life of components, and ultimately cause fractures and failure of wire leads, solder joints, etc.
The frequences we used were all in the audio range.
1999 Buick Park Ave Ultra
Head Unit: JVC KWHDR720
EQ: Audiocontrol EQL
Front Stage: Hybrid Audio Technologies Imagine 5.25 mids, Morel Maximo tweets
Sub Stage: Boston G3 10", 0.5 cu ft sealed
Amp: PPI Phantom 900.4
Rear Fill: Boston SE953 6X9's