The Ultimate Diesel Guide is a booklet about the diesels on the Island of Sodor.
- 'Arry and Bert
- Diesel 10
- The book was given away at Day Out with Thomas events and with DVDs in the UK and US. It was also available online.
- For unknown reasons, Class 40, Splatter and Dodge were not included.
- This book reveals Dennis and Norman are brothers.
- On the front cover, Salty's bufferbeam is not weathered.