Due to the success of these books, they went on to make other ones, including one for water cooled VW's like Rabbits. Even touched on how a diesel engine works.
The illustrations are the finest things about this series of books. Rather than use crappy photos that have neither perspective nor clarity, pen and ink drawings are used to detail what the part does, where it goes, and how big it is. You can get an idea of where you are in the engine compartment with these drawings, a blowup is often included.
If Haynes or Chiltons would get a clue and produce books like this, I'd buy stock.