The most commonly used CAD software for mechanical engineering is likely to vary depending on factors such as personal preference, the specific needs of the project, and the availability of the software. Some of the most popular CAD software for mechanical engineering include SolidWorks, AutoCAD, and Pro/ENGINEER. These programs offer a range of tools and features for designing and modeling mechanical systems, such as 3D modeling, assembly modeling, and simulation. Ultimately, the best CAD software for a specific project will depend on the specific needs and requirements of the project.