Here's how to unlock Tesla's new Ludicrous Plus acceleration mode
It's not something you want to leave on all the time, because it also accelerates wear to the car's drive components.

Tesla loves a good Easter egg, and its latest firmware update includes one that makes Ludicrous mode even more, well, ludicrous.
When loaded up with the latest firmware, Tesla's P100D vehicles can enter a mode beyond Ludicrous, which for now is just referred to as Ludicrous Plus. It's activated by holding down on the Ludicrous button for 5 seconds. After that, the instrument panel displays the battery's temperature and the outputs for both battery and the electric motors.
The mode unlocks an extra 35 horsepower or so, but it comes at a cost. A confirmation screen asks the driver to acknowledge that Ludicrous Plus mode accelerates wear to the battery, motors and gearbox. It doesn't appear to screw with the warranty, but it's something to keep in mind nevertheless.
While Dragtimes' video didn't produce any impressive numbers (it was raining), a tweet from Elon Musk seems promising. He claims a 0-60 mph time of 2.34 seconds using Ludicrous Plus, although that's using Motor Trend's methodology, which involves starting from a 5-mph roll. It's an impressive time no matter what, but it's not a true 0-60 time, per se.