ask owner about the computerized plates and the original file which is returned to owner after vehicle registration [ called return file ] if those are not issued officially, transfer the car. Only buyers CNIC & signed T O form is needed, with sale deed signed by current owner.
after vehicle is transferred apply for return file and number plates.
If the vehicle is registered after September 2011 and transfer is happening in Aug 2016 WHT will apply as well. [WHT is 50% after 5 years of 1st registration]