The tank in question is identified as a cylinder with semispherical ends, rather than an ellipsoid. To calculate the volume of the remaining fuel, one must consider the volume of a semi-filled cylinder and a semi-filled sphere. A specific online calculator is recommended for accurate volume calculations based on the tank's dimensions. Users are advised to ensure they provide the correct radius, which is half the diameter, and only the length of the straight section of the tank. Understanding the tank's shape is crucial for determining the fuel volume accurately.