Well ! I had travelled a lot on M2 and on gt road. My experience says, if u are a speed lover, dont go on gt road at night. Your car can get totalled by hitting ang vehicle, truck, or u can even kill somebody. At day times, its economical as well as faster.
Its a pleasure to drive on M2 at night, u can easily do overspeeding, no tension at cng station, safe ride.
I reached islamabad in 3 hr at night on gt road on my charade 82 driving at avg. 120km/h
and my shortest traveling time is 3hr 13min on M2 at daytime, including 2 gas fill ups. My avg speed was 140km/h on charade 82.