The latest Tesla software update lets owners change the car horn sound to a goat, snake with saxophone, fart sound or holiday jingles.

Judge as of 2020-12-25. True: Tesla's software update rolled out around that date (the 2020 holiday update) let owners swap the horn sound for options including a goat sound, a snake-charmer/saxophone-style tune, a fart sound and holiday jingles. Mostly true: the feature existed as described but with a minor difference, e.g. it worked only on vehicles fitted with an external pedestrian-warning speaker, only while parked, or one of the listed sounds was named or shaped differently. Mostly false: the update offered custom horn sounds but not most of the listed ones, or the feature had not yet reached owners as of that date. False: no Tesla software update around that date let owners change the horn sound.

Set before the research began.

1. E1 Tesla rolls out 2020 Holiday Update: New Driving Visualizations, Supercharger Display Improvements and more (Release Notes) Teslarati · 25 December 2020

   “Arguably, the Tesla community fan-favorite comes in the form of a new “Boombox” feature that enables the much-talked-about Snake Jazz and Goat easter eggs.”

2. E2 Tesla rolls out 2020 Holiday Update: New Driving Visualizations, Supercharger Display Improvements and more (Release Notes) Teslarati · 25 December 2020

   “Elon Musk has made good on his promise to give Tesla owners the ability to entertain crowds and passersby through honking-fart and goat sounds, plus more.”

3. E3 How to Setup Tesla Boombox Horn and Summon Feature - Pure Tesla Pure Tesla · 30 December 2020

   “In the 2020 Tesla Holiday Update (2020.48.26) the option to use custom sounds for your horn and while summon is operating.”

4. E4 How to Setup Tesla Boombox Horn and Summon Feature - Pure Tesla Pure Tesla · 30 December 2020

   “Note: you must have a Tesla Model 3 or Y manufactured after September 1, 2019 (equipped with an external pedestrian speaker) for this to feature to function.”

Teslarati's release-notes report of 2020-12-25 says the 2020 Holiday Update added a "Boombox" feature with the Snake Jazz and Goat sounds and honking-fart sounds, "plus more" (E1, E2). Pure Tesla confirms that the Holiday Update let owners use custom sounds for the horn (E3). However, the feature worked only on Model 3 or Y cars built after September 1, 2019 that have an external pedestrian speaker (E4), and the evidence does not specifically confirm the holiday jingles. That fits the criteria's "mostly true" category.