How accurate are speed cameras on Mumbai Pune expressway?

I have been fined for overspeeding and the snapshot shows 111 kmph against the speed limit of 100 kmph. I am pretty sure I didn't touch 100 even once - I regularly travel on this expressway and I make sure I stay within the speed limits. Also, my car is pretty bad at accelerating so it's not possible to get to this speed without intentionally flooring the throttle.