They don’t really have a negative CCC, unless you consider one or two days. That’s because you order your car and pay only about $100 (sometimes refundable, and negligible compared to the total cost of the item). Then you pay the balance the day, or a day before, you take delivery.
Meanwhile, the company paid for much of the materials and labor in advance of that. Maybe there are some suppliers at 30 days or maybe even 60 days, but I suspect very few of those because of the high level of vertical integration at Tesla.