There's variable bit rate mp3, so it varies depending on source material. That said, 10 hours is a rule of thumb. You put albums until CD is full. And car on a

There's variable bit rate mp3, so it varies depending on source material. That said, 10 hours is a rule of thumb. You put albums until CD is full. And car on a highway is not an environment differences between bitrates really matter. Also, "play album by foo" voice command doesn't really work when you have non-english names. Or even english based names when you're not a native speaker with good pronunciation.