I\'m aware of manual guides to upgrade from 3 to 4 like this one: http://www.dotnetexpertguide.com/2011/12/upgrade-aspnet-mvc-3-project-to-mvc-4.html
The guides vary
An auto-upgrade now exists.
Check this out: http://www.dotnetexpertguide.com/2013/02/aspnet-mvc-auto-upgrade-mvc-3-to-mvc-4-application.html
It is a Nuget Package called UpgradeMvc3ToMvc4