Driving in Islamabad would be a scary experience. In my time in Islamabad I just caught taxis and public transport but on the roads it seems to be a free-for-all! Our trekking company's owner remarked that once and trekker had asked "which side of the road they drive on in Pakistan?" to which he replied "they drive on the left................and on the right and straight down the middle!".
The street scenes are great with a mixture of the beautifully decorated buses with blaring horns playing tunes to the black and yellow suzuki taxis- with their proud owners, to expensive Mercedes and bicycles, carts and pedestrians all thrown into the bargain!
If you have to drive I guess you just have to keep your road sense, and sense of humour!