Usually LP's are allowed to exceed the sanctioned speed limits for a short duration. Another member on IRI previously posted an RTI request for the same, and while I don't remember correctly, LP's can exceed the speed limit by 3kmph for about 5 minutes, and by 5 kmph for 2 minutes (Again, I am not sure about the duration). And GPS speedometers can show an error of +/- 5-10 kmph frequently, especially when sitting inside a metal railway coach, with many obstructions all around. So, some over-speeding might definitely have been there, but probably not 169kmph as you saw.