What CAD software is most commonly used by Mechanical Design Engineers?
It really depends on the discipline. For instance the majority of Automotive and Aerospace companies use CATIA or Unigraphics. While some automotive use Pro/Engineer in pockets, this is limited. However most heavy vehicle (trucks, tractors, dozers, etc.) use Pro/Engineer. The mid-range CAD market (AutoCAD, Autodesk Inventor, SolidWorks, SolidEdge) are all used in the manufacturing realms (special machine, tooling, fixtures, etc.). AutoCAD 2D still has a 10:1 market share over all other products combined in that market, but AutoCAD 2D use in new designs is dwindling and the use of SolidWorks and Inventor are growing in double digit percentages. If you’re planning on working for an Automotive OEM, Tier I or Tier II or Aerospace I would suggest CATIA or Unigraphics classes in school. If you’re planning on anything else pick whatever 3D CAD package you school offers, the mid-range packages are all similar in functionality and you can learn one if you know another.