no issues with the car you are taking....have just completed a trip mid July Lahore to China via Khunjerab Pass and back to Gilgit up to Ghizer Valley, then back to Lahore via Babusar Top on 2016 Altis 1.8....Skardu,Naltar Valley and Deosai Plains trip we did on Jeep as it was not car friendly at all...as you are going to take only KKH, so will tell you road conditions for the road you are taking......one patch from Chillas to Raikot bridge is under construction which is about 15-20 kms...most of this distance has not been carpeted (as of mid July 2018), but you can drive slow...nothing to worry about....I myself was only doing max 20kmpl as didn't want to ruin my car and I suggest you do the same....rest road is all carpeted...no problem going at over 100 kmpl...just you need to be cautious about other drivers, mostly local as they all drive NCP and not following lane rule....as long as you are cautious, no need to worry....also be careful around bends as you will see people coming in your direction..khunjerab pass gets very cold, so especially for little ones and also adults, keep warm clothes handy...you will find plenty of petrol pumps on the way so no need to carry extra petrol, quality of petrol is not good so better to fill a tank or two with High Octane when you reach Islamabad...had trouble starting my car on Babusar Top due to the fuel I had been putting in but could be I got a bad lot.....lastly just enjoy the trip and drive safely