The new mode shows up as a reindeer icon within Tesla's Easter Egg Menu. Press that flashy reindeer and you'll see Santa showing up on the instrument cluster. Oh, and this is just half the fun, since you can also use voice activation for the feature. Sure, this might seem a bit strange to those in the cars next to you, but perhaps you'll get them in the holiday mood too.
It's simple, really - press and hold the car's voice command button and go "Ho Ho Ho". These instructions come from Elon Musk himself, who took to Twitter two days before Christmas to deliver them.
When you get the new Tesla software update, go Ho Ho Ho. There’s an Easter egg inside the Easter egg, but it’s not funny.— Elon Musk (@elonmusk) December 23, 2017
Now that you're in Santa Mode, the vehicle icon on the instrument cluster shows Santa's sleigh, which is obviously loaded with gifts (supposedly, just like your Model S or Model X).
As Autopilot detects nearby vehicles, you'll see these in the form of prancing reindeers. Also, the Autopilot feature will turn the digital lane indicators into a snowflake-loaded icy road.
Even if you don't happen to own a Tesla Model X or Model S, you can check out the Sant Mode Easter Egg in the piece of footage below, which comes from Brooks of the Drag Times YT channel.
P.S.: This cabin-focused Easter Egg follows the Holiday Show feature we received last year, which was built around the exterior of the EV. You know, the one that puts the Tesla Model X Falcon Wing doors to acrobatic work while playing Wizards in Winter.