When the Autobots first came to Earth, they were still in their "Protoform" state, without Earth based vehicle modes. To adapt to their new world, they all took on new forms. Ratchet took on the form of a rescue Humvee vehicle. As part of the Toys R Us exclusive "Mission Earth" line, Ratchet has been released representing the moment he changed his form. Check out my review of "Scan Series" Autobot Ratchet!