Over several conference calls they have roughly answered this. Their biggest limitation to what they want to do is engineering talent. And they want to grow rea

Over several conference calls they have roughly answered this. Their biggest limitation to what they want to do is engineering talent. And they want to grow really fast. So using scarce engineering talent to improve an existing process slightly is not aligned with those goals. They want all the talent building new factories and products. They do seem to still have small teams to make continuous improvements, and eventually those upgrades like the heat pump and improved body will be integrated. I think Elon guessed several years at a minimum on a call.