Are the Chinese cars somehow really doing manufacturing more efficiently or is it a flooding of the market to capture the market and drive out encumbants (whether government subsidized or otherwise)?

I just don’t understand how the Chinese are making cars at half the price or more since afaik they also manufacture them in China and ship rather than build locally.

I worked in the industry. It would have been really hard for China not to do better. Like really hard. They allocated 2 years, 150 people for a device that already existed but needed to be adapted to a different customer. It took 2.5 years. No improvements added. Every single manager in those companies is very political, no skills, technical or otherwise. So if chinese hired 20 competent people, gave them training on the industry's specific tools, they are already ahead.

They have dark factories ...

https://www.youtube.com/watch?v=MCBdcNA_FsI

Look at the population of your country. Look at the population of China.