The term 'Fossil-Fuel Hauler' refers to a person who transports fossil fuels such as coal, oil, and natural gas. The 6-letter term for this job is 'Coaler'. Coalers are responsible for the safe and efficient transportation of these materials from one location to another. They must be knowledgeable about the regulations and safety protocols associated with the transportation of these materials. Additionally, they must be able to operate the necessary equipment and vehicles to transport the materials.