The car can not be transferred to Islamabad if you mean transferred with regards to the registration,
Make sure the car has the original registration book and signed on the transfer page,
Check to see you have the ID card photocopy of the registered owner,
Sales deed, transfer letter, check with CPLC to ensure the vehicle is clear, get verification done from Civic Centre,
In order to transport it you need a letter from the seller saying he would like to have the vehicle transported to islamabad, get a NOC from CPLC, contact a vehicle transported (plenty near hawkesbay) drop the car off to them, fill out their documentation to ensure the car is received in Isb in the same condition and with the same accessories in place and thats it.
I would ideally also pay for transit insurance, usually provided by Adamjee and doesn't cost much, its according to the value of the car.