For Tesla CEO Elon Musk, working with his peers to expand the budding market for electric cars seems more important than competition.

One of the US electric car maker's top competitors in China, Nio, saw its 100,000th mass-produced vehicle roll off the production line at its manufacturing site in Hefei, Anhui province, on April 7.

It was a major milestone for Nio, 35 months after its first production vehicle, the Nio ES8, rolled off the production line on May 27, 2018, and earned Musk's blessing.

Musk commented on a story covering the development on Twitter saying, "Congrats to Nio. that is a tough milestone." He currently has 50 million followers on Twitter.

So far, the average sales price of all Nio models is RMB 428,000 yuan ($65,321), much higher than the average price of all other local car companies, even Tesla in China.

For Nio and Tesla, although jointly expanding the user base of electric cars is the most important goal, they cannot help but occasionally show their teeth to each other in the competition.

(Source: @TheIronGiant8)

"Now that Nio's average unit sales price is about RMB 150,000 more expensive than Tesla's in China, our users and Tesla users are no longer quite in the same category, and there is already a significant distinction in the brand segment," Nio founder, chairman, and CEO William Li said at Nio's 100-degree battery pack launch on Nov. 6, 2020.

He said that Nio's average selling price is already above RMB 400,000. This statement reveals Li's judgment that Nio's user base is slightly higher than that of Tesla.

Li probably didn't expect that this statement would soon receive a response from his rival.

A dozen hours later, Musk tweeted, "420 is ten times better than 42!"

On the same day, Tesla's share price fell to $420 per share, while Nio's share price rose to $42 per share against the trend, based on which Musk's tweet was seen as targeting Nio.

This is also the first time that Chinese and American new car makers verbally competed with each other on the Internet.

On Feb. 28 this year, Tesla added "sales of battery swap facilities for new energy vehicles" to its business scope in China, sparking speculation that it might support battery swap like Nio.

Beijing Business Today later quoted the company as responding, "Tesla will not adopt battery swap."

Tesla subsequently removed the sale of battery swap facilities from its scope of operations in China.

Grace Tao, Tesla's vice president of external affairs, said on Weibo that Tesla believes charging mode is the best way to supplement power for large-scale residential electric vehicles. She said battery swap facilities should primarily serve public transportation, and that high-power fast charging is more convenient and stable for the average user.

She also used the evolution of electronic products in the past 10 years as an example, saying that these products initially used removable batteries, but now they have become integrated built-in battery design. She said that fast charging is actually "the result of deep thinking by major electronics manufacturers in terms of technology trends and product logic.

Although Tao did not directly name Nio, the company is currently the only one in the Chinese market that has launched battery swap-enabled models for general consumers.

Ma Lin, senior director of communications at Nio, said on Weibo that battery swap stations are important infrastructure for Nio, taking into account user experience and user interests, "whether battery swap is good or bad, users have the most say.