I'm having all sorts of problems doing this and the supplier of the car phone assures me it is the phone and not the car kit that is at fault.
Sometimes I can't get any of my contacts to go across to the car, sometimes I get some but not all, sometimes I don't get any.
Under 'Contacts to Display' in the S4, is there a particular one I should select? I've tried a few without success!
Or has anyone got any more ideas of what I could try?