The headline is misleading, but they immediately follow up with a qualification that makes the headline technically not wrong. They're saying just market value of the equity. That can be very different from market value of the enterprise, which includes the market value of all financing: debt as well as equity.
The metric they're using is not necessarily a meaningful way to rank the "biggest," or even "most valuable" auto making operations.
"Tesla delivered an impressive number of 112,000 vehicles during the final three months of 2019."
I get that people like this company, but this isn't even as credible as pop stars who've been said to be more popular than The Beatles ever were because of the increased number of people listening to music: GM sold 10 million cars in one year just a few years ago.
Ford produces 6,000,000 vehicles per year with revenue of $160Bn and circa 200,000 employees.
Please explain to me what big means again? Most valuable maybe, but I don't think 'biggest' is a reasonable description.