I purchased the latest MacBook Pro retina in November 2013, its the 15″ version which has two video cards on it, an Intel Iris and an Nvidia 750M if I recall correctly.
Its nice to have two video cards because you can do more graphic hungry stuff without having to use another computer, but there are times where you really need as much battery as possible, and you don’t want any application to trigger the power hungry Nvidia 750M.
OS X doesn’t have a way to disable one or the other, so after searching online I found a very nice application called: gfxCardStatus. Its free and will allow you to configure which card should be used on your MacBook Pro.
You can set it to Dynamic Switching (default), Integrated only or Discrete Only.
My opinion is that Apple should allow you to choose this from System Preferences directly and also let you choose which applications are authorized to use the Nvidia card or not. It happened to me already with several applications that they are using the Nvidia card when they don’t really need it. Nowadays playing a movie on your computer with the embedded Intel Iris card should be enough and when you are on battery this will save you a lot of battery. Also I´ve noticed some bugs from applications that even are non graphic related that trigger the Nvidia card, this can produce a lot of battery drain if you don’t have a way to easily notice which application is using which card. With gfxCardStatus you would be on the safe zone 🙂 I am so happy with this app that already donated some bucks to the developer ;).