"We have two more events we are in discussion with: Croatia and New Zealand. Croatia seems entirely feasible, but we cannot find the date in the holiday season.
"It was not possible to reorganise the entire second half of the season to squeeze [Croatia] in.
"From the last consultation with the teams regarding New Zealand, the costs of this as a 14th event are not what they budgeted and not what they would support.
"This means New Zealand is not likely to be on the calendar.
"When we see the passion with which the New Zealand organisers fight for this, we would really love to come but it seems the economics for a very big event are just not coming."
The motorsport world is in a transition phase with a number of big manufacturers opting to move away from traditional motorsport markets and focus their attention on Formula E and an electric future.
What is likely to change for next season is the move to four-car teams. At present teams have three nominated drivers with the top two scoring points. It is proposed that a move to four-car teams and three point-scoring places replace the current system.
This would expand the driver market significantly and help cater for a number of promisin young drivers to burst to prominence this year.
