Some have an AWD drivetrain which goes on automatically depending on the need. The car's computer system will know, e.g. when one or more wheels spin on a slippery road. You do not have a way of turning it on manually. However the 350S version has a button for the diff-lock where you can engage the 4x4 manually. The 350S is a 3.5cc engine and that is why it is not so popular.