OK, I don't actually own a VW Beetle. But if I did, this'd be exactly the book I wanted -- extremely well written guide on maintaining a Beetle at home with minimal tools, with detailed explanations of how things work and great diagrams. I wish this kind of book were possible for a modern car...
(There are lots of editions of this, but as far as I can see the bulk of the text is the same; mine's a 90s reprint.)
ISBN 1562611909.