All these vehicle iterations were made for Vertex 3 – thanks again to Art By Papercut for this, it’s been a BIG BIG BIG honor – you can download the book for free here – http://artbypapercut.com/
The description given from papercut for the article was:
The function a vehicle has in the level when placed by artists or designers. This tutorial is not so much about modeling. But more about thinking about what you are modeling for the game more regardless if its a vehicle or a chair.