The frame and car shell are manufactured in the stamping workshop. Some engines are made by ourselves, and some are made by other professional manufacturers. Gearbox At present, all major automobile manufacturers adopt the products of the world's three major gearbox manufacturers. Tires are also from other manufacturers.
No one can give you accurate information, because it is a trade secret. Some of them are developed and manufactured by its wholly-owned subsidiaries, some are outsourced to other companies, and some are directly purchased from other companies' products.
But a powerful automobile manufacturer must have the ability to develop engines and gearboxes!