I have travelled from Karachi to Faisalabad & then north to Islamabad like 20 time....Not even once I have been stopped except few times initial and that also in Sindh...and since I belong to a military fam background so they although have trouble us like almost none but have showed them the card and they let us go!!!
We used to leave Karachi at morning 6am and used to have a stay-over in Bahawalpur Cannt Area by maximum 6pm and next day 5 hour journey to Faisalabad and 2.45 further to Isloo after staying for a day in FSD.
We have Honda City EXIS 2001 A/T, and our latest fuel (CNG) kharcha comes to 5500 and this info is I am giving you of Nov 2011 journey till Islamabad from Karachi....
since I love long driving, I hate taking mid-stops except CNG....we used to reach rohri by 1200pm-1230pm!!!
Have safe Journey...Again, we never opt for any NOC or anything...nothing happened to us and we enjoyed it everytime!