Reference: I’laam al-Mu’aasireen bi-Fataawa Ibn ‘Uthaymeen – Page 196
Question: In some cars, the audio speakers are at the level of the feet, and sometimes the feet and shoes are actually on the speakers. [So] the question is, when the Qur.aan is played on the in-car audio system, will this then be considered degrading the Book of Allaah?
Response: If the audio speakers, as mentioned, are indeed beneath the feet and shoes, then the Noble Qur.aan should not be switched on [to play on the in-car audio system]. This is because the Noble Qur.aan will then be heard from beneath the person’s feet, and there’s no doubt that this is an insult to the Qur.aan.