Nio's first vehicle rolled off the line on May 27, 2018. It saw its 100,000th mass-produced vehicle roll off the line in April 2021, when Tesla CEO Elon Musk expressed his congratulations.

Nio's (NYSE: NIO) 500,000th mass-produced vehicle will roll off the line on May 9, local automotive media outlet Auto Home reported today.

The electric vehicle (EV) maker delivered 15,620 vehicles in April, bringing cumulative deliveries through the end of April to 495,267 units, close to the 500,000-unit mark.

Notably, the delivery of the 500,000th vehicle will happen some time after the 500,000th vehicle rolls off the production line, considering factors including logistics.

Nio was founded in November 2014, and its first mass-produced vehicle was the ES8, with the first unit coming off the line on May 27, 2018.

Deliveries of the ES8 began in June 2018 and 100 units were delivered in the first month.

On December 15, 2018, Nio held Nio Day 2018 in Shanghai, its second Nio Day. It unveiled its second production vehicle, the ES6, at the event, and the lower-priced SUV has been one of Nio's sales anchors so far.

The company saw its 100,000th production vehicle roll off the line in April 2021, when Tesla CEO Elon Musk expressed his congratulations.

"Congrats to Nio. That is a tough milestone," Musk tweeted at the time. The Tesla CEO had later acquired Twitter and renamed the platform X.

Later in April 2021, Nio delivered its 100,000th vehicle.

On April 26, 2022, Nio saw its 200,000th production vehicle roll off the line and delivered its 200,000th vehicle about a month later on May 15.

The company's 300,000th vehicle rolled off the line on December 12, 2022 and was delivered in February 2023. Last November, Nio delivered its 400,000th vehicle.

Nio is expected to hold a ceremony at one of its two plants in Hefei, Anhui province, to celebrate the 500,000th production vehicle, at which time it is expected to unveil information about the sub-brand Onvo.

Onvo's management team will be unveiled on May 9, and the brand's head, the meaning of the brand and logo, and information about the Onvo App are expected to be announced, an auto blogger said on May 6.

Nio to launch sub-brand Onvo on May 15, report says