I always buy used cars in my life(30 year driving experience). I think this law is useless for me. Even if this law can be applied on used cars (the chance is very low), I think I still don't need it... 
Of course Japanese could make errors also. If I encounter a lemon car from them, I think I should buy a lotto...
(too lucky or too bad luck??? I'm always NOT a lucky person SO FAR...)
練習我的英語! Use Goolge Translate if needed.