Diesel is a troublesome character who is ever ready to scheme and stir up trouble.
- 1993 (staples, flat magnets, undated wheels)
- 1994 (no staples, flat magnets, undated wheels)
- 1994 (no staples, round magnets, wheels dated 1994)
- 1996 (smaller magnets)
- 1997 (thicker wheels, larger magnets)
- 2002 (back ledge removed)
- 2005 (updated details and face, red bufferbeam)
- 2011 (CG style face)
- 2013 (updated details, updated face with smile, curved edges and longer magnet guards)
- 2017 (black bufferbeam)
- 2018 (printed details on exposed wood, unpainted chassis, flatter face)
- 2019 (printed details on painted wood, three vents near cab)
- Bronze Diesel
- Oil-covered Diesel
- Talking Diesel
- Battery-Operated Diesel
- Snowy Diesel from Snowy Mountain Figure 8 Adventure
- Milk-Splattered Diesel from Diesel's Dairy Drop Off
- The 1994-2012 versions of Diesel are some of the few vehicles that do not smile.
- The prototype 1994 Diesel features no eyebrows, sticker cab details, and no engine/vent detailing.