From TF2 Wiki
- The name and fiery flame design is a reference to American cars with large engines, also called hot rods, which often have a fiery paintjob.
- The Hotrod flips down over the Engineer's face when he is holding a building's blueprints or hauling a building, currently making it the only hat to possess its own unique animation.
- Additionally, a Spy disguised as an Engineer currently wearing a Hotrod can have the hat flip down on his face by equipping the Electro Sapper. This can be used to detect Spies.
- The Engineer wears the Hotrod in addition to his goggles. In reality, the smoked glass of both the welding mask and his goggles would make it impossible to see. This may be why he normally wears the Hotrod in the raised position.
- "Hot Rod" is also the title of a 1979 movie, in which Grant Goodeve, voice of the Engineer, starred.
- It is interesting to note that the late Robert Culp, the voice of Dr. Breen from Half-Life 2, also co-starred in this film.
- The Engineer is seen using a welding mask in the teaser video for the Engineer update, though it is not the Hotrod. The Hotrod, however, can be seen sticking out of a tool chest at the very beginning of the video, above the Engineer's acoustic guitar.
- Valve wanted to make the Hotrod paintable, but failed to get the creator's permission.
- The Hotrod is undoubtably the most sought after Engineer Hat (the second most sought after being the Texas Ten Gallon). A new version Hotrod is typically traded for 2-3 refined metal, whereas a vintage Hotrod would be traded for 4-5 refined metal.
- Wikipedia: Hot rod, retrieved November 8, 2010.