"On the Fly" Manufacturing

Scrambling to turn out its first mass-market electric car, the automaker set up multiple assembly lines and is changing production processes on the fly.

The New York Times asks Can Elon Musk and Tesla Reinvent the Way Cars Are Made?

The subtitles in bold below are mine and I reordered a few paragraphs.

Just two years ago, Mr. Musk envisioned 2018 as a breakthrough moment. Having established the brand's cachet with high-end offerings — the Model S luxury sedan and the Model X sport-utility vehicle — Tesla would begin churning out more affordable Model 3 sedans.