I lent my friend a car and now the audio player isn't working; who is responsible?
I let my friend use my car, and now the audio system isn’t working. Can I hold him responsible?
The short answer is, no. The reason is that it would be difficult to make a compelling case in front of a beis din that the audio system wasn’t broken when the car was borrowed. Moreover, even if the borrower concedes that the system broke while they were using it, they would still not be liable due to the principle of meisah machamas melachah: a shoel (borrower) is not liable for damage to a borrowed item that occurs as a result of normal wear and tear as long as it’s being used for its intended purpose. In this instance, granting the borrower the use of the car implicitly included using the vehicle’s audio system; therefore, any damage that occurred during normal use would fall under machamas melachah.
In practice, if such a dispute arises it should be brought before a rav.