The tally relies on reservation numbers posted by new reservation holders on the Tesla Motors Club forum. Members post their sequence number for their region and version of the vehicle (signature or production). A summary tally of the highest numbers reported to date is regularly updated to show the current tally total.
The total is now 31,195 reservations with deposit, but Carter’s analysis take into account possible cancellations based on the tally’s total when Tesla confirmed having approximately 20,000 reservations in December 2014, which could bring the total down to 26,892 reservations.
On August 31st, Tesla opened the online design studio for a select few Signature reservation holders to configure their vehicle. Now that more information about the configuration of the Model X is available, it will be interesting to see how it will affect reservation data.
Here’s Carter’s update: