Dart is the latest addition to the Depot and the website arriving before the release of the 2011 special.
Dart's description reads; Dart is Den’s fast and feisty assistant at the Dieselworks. Dart has worked with Den for so long, he can read Den’s mind. Together, they run the Dieselworks well.
Dart will quickly explain what Den is trying to say. No other Diesels know how to fix an engine as quickly or as capably.
The last Day of the Diesels character to emerge from it's silhouette will arrive in the Engine Depot in a month's time.
Thanks to ThomasPercyandToby2 for the alert.