Considering Net Zero for the heavy vehicle transportation, sustainable diesel fuels can be the right-the-way solution, compared to the electrical driven power source. Additionally, some sustainable diesel fuels are produced from “renewable” wastes, which hugely contribute the carbon neutral mission. The use of transestificated biodiesel was the solution for reducing carbon emissions. However, the disadvantages of high NOx emission, high unregulated emissions (formaldehyde, acetaldehyde), power performance, and storage problems keep away from the heavy truck drivers. The novel sustainable diesel, hydrogenated renewable diesel (HRD), has greatly resolved these issues and been more and more popular recently. However, the physical characteristics of HRD, depending on the feedstock source, hydrogen usage, production process operations, are varied batch by batch. The most significant characteristics for this new type of fuel are spray and atomization, since they are strongly linked to the air-fuel mixing, ignition, and combustion behaviors afterward, which largely contribute to the power performance and emissions. Among the spray characteristics, the spray penetration and evaporation behaviors are the most important factors, especially under various high temperature and high pressure conditions. An optical engine or combustor equipped with high speed camera is required for studying these behaviors. Thus, this part of field has not yet been discussed from fuel, engine, and combustion researchers. Examining this physical characteristics of the sustainable diesel fuel can help the fuel makers to adjust the process conditions, or even choose more proper feedstocks. Overall, this study will contribute not only the carbon neutral for diesel engine users but also SDGS 7 Affordable and Clean Energy.