Other EV makers in China, including BYD , offer their partially automated driving systems for free or a much lower cost.
Xiaomi's popular model SU7 includes the company's equivalent technology as a standard option for free.
The latest slide followed a report from Reuters on Monday that Tesla's long-awaited upgrade to its partially automated driving systems left owners disappointed.
Many users told the publication that Tesla's "navigate on city streets" feature in China fell short of Musk's promises for self-driving technology.
The stock has plummeted 25% to start the year, while the Nasdaq is down just 1.5%, and has slid more than 35% from its record close on Dec. 16.
Shares of the electric vehicle maker plunged more than 8% on Tuesday, pushing the company's market cap below $1 trillion and to its lowest since Nov. 7, which was two days after President Donald Trump's election victory.
Most of what remains of the rally is due to the stock's 15% jump the day after the election. »