How old is your car/CD player? We have a 2001 and a 2002 vehicle, neither of which can play them. But after the technology became widespread (just a couple of years later), virtually every car with CD player was capable of playing them. I'd say if your car/CD player is 2005 or later, it probably is.
Also, if you were to buy these and they would not play, you could still transfer the mp3s to a blank audio disk and listen to them that way. You can't cram a bunch on a CD like you can with a mp3 disk, but you could get one or two on their, depending on the length (an audio CD has to be 80 minutes or less). It's pretty easy to do and if it comes to that, PM me and I can talk you through it.