It will be fine.
You wont set fire to anything under the car thats jut not realistic.
You might get a headache, you might feel tired, your ears will probably be ringing when you get there, but in real talk, you wont do the car any harm.
Just be aware that if you do get pulled over, the police can do something about it (dont quote me on what)
I wish people on here would just answer the question asked and not other things. I think it is fairly safe to assume that this guy knows what happens when something is loud for a long time. give the him some respect and assume he has some common sense.
Thanks for the comment, I was under the impression that it might be fine police-wise since i'll ******* and say that it just happened to be dangling off when I was at the service station, and so I removed it safely and placed it on the backseat.