It's a tricky one. I've got an anorak's song-book, printed out on filofax paper, which I annotate with the place and the date in pencil.
Doesn't stop me flogging the same old stuff to death, though - I must learn some new songs, but CRS keeps kicking in.
For getting the song ground into the brain, the car's not a bad option - providing you don't mind sometimes looking like a total tit when you pull up at the lights with the window open and a rousing chorus dying on your lips as the cyclist looks down at you in astonishment.