Thomas and the Evil Diesel, retitled Thomas and the Naughty Diesel in American releases, is a book written by Christopher Awdry.
When Percy has to go to the Works for repairs, Diesel returns to Sodor and, as expected, causes trouble for the engines by destroying the oldest truck in Ffarquhar Yards. But two days later, Thomas has an accident when Daisy drips her oil on the track and Clarabel's back wheels come off the rails at the special points at Dryaw, so Diesel comes to the rescue. It seems that even Diesel has some good in him somewhere.
- Sir Topham Hatt
- Daisy (does not speak)
- Annie (does not speak)
- Bertie (does not speak)
- Gordon (cameo)
- The Random House release has unrealistic illustrations.
- This marks Diesel's second appearance on Sodor.
- The Random House release, narrated by Robin Smith, was used as a bonus feature on several US DVDs.