Light Duty Vehicle corporate average fuel economy (CAFE), fuel economy label, and greenhouse gas (GHG) requirements are related but are very different. The fundamentals to obtain the data are the same, but to derive the required values, the final formulas have different components. These formulas, how to obtain the values which comprise the formulas, and how to use the test output to obtain the final result necessary to determine compliance with the standards are in regulations, but are not easily located. The information is contained in many documents; such as various sections in the Code of Federal Regulations, U.S. Environmental Protection Agency (EPA) Guidance documents, SAE International papers, American Society of Testing and Materials standards, and law suit judgments. This paper compiles the fundamentals of vehicle CAFE, fuel economy label, and GHG information. The intent is to provide a reference to the foundation of these requirements. This paper should not be used for compliance purposes and the actual regulations need to be referenced.