Well have you tried listening to it with headphones and without any distractions? It makes the songs seem less lengthy to me because when you're concentrating you can hear something new every time they repeat a section. I don't know. I just know it is much better for me when I can focus on just the music.
Opeth just doesn't fit the "headbang in your car" thing for me. Maybe I'm just dumb and can't concentrate on music and other things at the same time.