The automaker asked the National Highway Traffic Safety Administration (NHTSA) to declare the noncompliance issue inconsequential to safety.
Tesla said it corrected the issue in production in September and that more than 75% percent of the affected US vehicles have accepted the firmware update released in September.
The launch of the ET7, at an event in China's western city of Chengdu, comes as rival Tesla started selling its China-made Model Y sport-utility vehicle.
Chief executive William Li said Nio's new battery technology will give the ET7 a drive range of over 1,000 kilometres (621 miles) between charges.
It is also adding manufacturing capacity for EV chargers in Shanghai and expanding its sales and service network around the country. It sold over 20,000 vehicles in November.