Hyundai India has apparently taken the decision to make the gearbox of the i20 diesel with only five cogs rather the six that it had been upgraded to sometime ago.  The reason cited is that the engine and gearbox of the i20 are the ones that do duty in the new Verna that has been recently launched and  Hyundai believes that there should be better differentiation between the two products since the Verna is significantly more expensive than the i20.