As you said elsewhere, Trump says more than enough stupid shit - including in that very same speech, in fact, including in that sentence - that it's unnecessary and counterproductive to deliberately misinterpret / misrepresent his words.

It's still complete nonsense, mind you. First article I got in Google informed me that:
- Mexico currently exports about 3.3 million cars per year, most of them to the USA. However, at the same time it imports cars for its own domestic market from China.
- The new factory that a Chinese car maker is considering to build would make 150 000 cars per year, intended first and foremost for the local Mexican market.
- Potentially they might also consider export to the US in the future, but as the Mexican expert quoted in the article immediately adds, 'it will not be so easy for Chinese assembly companies to enter the U.S. market on a large scale because they have many protection measures for their national producers'.

In short, he's making up scare stories about something that is already happening today without anything like the impact he describes (ok, the Mexican factories exporting to the USA aren't currently owned by Chinese companies, that part might change, but what does that matter for American jobs?), then then making grandiose claims about how he's going to solve this non-existing problem, while pretending that Democrats wouldn't do anything if in fact anything remotely like this happened.

After all, Biden is making the same protectionist comments as Trump in the whole Nippon Steel situation - reminding me of a similar controversy back in the Bush presidency, then about an Emirati company wanting to take over American ports. As always, Americans from both parties are in favour of free trade when it involves American companies expanding abroad but dead set against it when it involves foreign companies expanding in the US. Though of course most large countries globally are just as hypocritical or even more so on that topic.

One imagines that for a minute there he actually listened to the army of consultants telling him that until the election actually happens, he needs to make people think their vote for him will make a difference and is sorely needed, hence the scare stories about what will happen if they don't turn out to vote for him. Then afterwards if he loses, he can start talking about it being stolen again.