Tesla's coming Cybercab could be a big win for the stock if the robotaxi math works, but the numbers are tighter than the hype suggests.

• Tesla's new "unboxed" assembly method builds cars from snap-together chunks instead of one long line, and Elon Musk says it could make cars up to five times faster.
• That speed plus a smaller factory footprint could cut build costs roughly in half and push Tesla's profit margins back up.
• The catch is demand: the Cybercab is a two-seat, two-door car, so almost all buyers will be fleet operators doing cold math on whether it pays.
• At about $1 per mile in fares, an operator financing the car at current interest rates only starts making money past roughly 20 rides a day — slightly better than Waymo manages now.
• Timing has already slipped badly; robotaxis were supposed to be commercial by 2024–2025, and mapping each new city's tricky spots still takes months.

Outlook: The stock's next leg depends on how fast Tesla can map new cities and whether ride prices hold near a dollar a mile once millions of these hit the road.