I think the set consists of 23 volumes. They were published in 1974 and is basically an encyclopedia related to cars. It's pretty well done and interesting to browse through. I have the entire set already (purchased a long time ago from a Salvation Army store, I think...).
You can see the dirt on the spines. It cleaned up nicely.
After Cleaning... In real life, there's a noticeable difference but the pictures don't show it...