Munro Live has posted a walk through Tesla’s Cybercab factory line with Lars Moravy, Tesla’s vice president of vehicle engineering, and engineers from his team. It covers how the car is built in separate modules, the battery pack, the drive unit, the thermal system, and the plastics shop that replaces painting.
Final assembly, where the modules come together, is about 25 stations and fully automated, Tesla’s team said on the stream. Munro’s host guessed a Model Y final line is five to ten times that, and Tesla said it depends on the plant. Across the whole line, the team put automation at about 78% today.
How the unboxed build works
Tesla calls the process unboxed. The team said the idea started five or six years ago, when it kept adding automation and found that “the problem wasn’t the automation, the problem was the design.” Smaller modules let robots reach parts from several sides. On the front module line, the pitch between stations is about 2 meters. Tesla says the layout uses about 50% less floor space per car built, and that cut was a target from the start.
1. Split the car into modules
The car is split into a front, rear, two sides, a center (the battery pack with the seats on it), and a top. Each module is built and tested on its own line, then the modules are joined at the end.
2. Build the front module
The front module holds about half the car’s parts. That includes the 48-volt low-voltage battery, the drive unit, and the thermal module. It arrives at final assembly already tested with its computers connected. Splitting the car also forced a brake-by-wire system, Tesla’s first. With no hydraulic lines running between modules, the front and rear brakes are tested separately. The front suspension is a strut, with the kingpin moved ahead of the wheel center to fit under the low hood.
3. Build the sides flat
The side modules use a single-piece inner and single-piece outer boron steel door ring, sandwiched together to protect the cabin and battery in a side crash. They are built flat on a bench, which the team said helps both workers and robots. The framing line is 100% automated, including parts delivery by mobile robots.
4. Lower the body onto the drivetrain
The drive unit, suspension, and thermal system sit on a pallet, and the body is lowered onto them, the reverse of how most plants install a subframe.
5. Put the wheels on last
Wheels go on at the second-to-last station, so the first time a Cybercab sits on its own wheels is when it leaves the line. Tesla also said the line can currently build faster than the company is deploying cars, so it does not run every day.
No paint shop
Only the side modules are e-coated. The front and rear modules are not. Tesla said its casting alloys do not lose strength from oxidation the way other aluminum does, and the team chose sheet alloys and joining methods to match.
Body color comes from the plastics shop. “This is our paint shop,” Tesla’s head of plastics said. Panels are made by reaction injection molding, with color mixed in at the mix head just before injection. Robots trim the overflow that keeps sink marks and flow lines off the Class A surface. Tesla said scratches can be repaired like normal paint. It also tried in-mold lamination, now used on the Semi, and a painted film on stamped panels.
Without a paint shop, unboxed panels do not have to be reassembled into a body just to go through the ovens.
Battery pack
The pack uses 4680 cells in what Tesla’s battery team called an 88S6P layout, with room for a few more cells and space under the modules for LFP later. The pack top cover is the cabin floor, and the seat crossmembers are welded to it. The enclosure is steel, a first for the program. The team put steel at about $1.90 per kilogram, against $5 to $8 for the material it would otherwise use, and said the cost still wins after the extra mass. It added that it is “still learning” whether steel was the right call.
Tesla calls this pack semi-structural. Potting is done per module, not across the whole pack, so a failed module can be replaced instead of the pack. The battery team graded its own work: Model Y’s structural pack got a D, Cybertruck a B-minus, and Cybercab an A-minus.
Other changes:
- Wireless communication between the battery management boards, deleting the internal harness
- No pyro fuse; the contactors can open under load and keep working (Tesla has filed a patent application)
- High-voltage blind-mate connectors, checked by insertion force and distance instead of a visual click
- Pack electronics service from below, because field data shows cells fail less often than the electronics
Drive unit and thermal
The Cybercab is front-wheel drive. Because it does not need a high top speed, Tesla’s drive unit team said it went to an 11:1 gear ratio, against roughly 9:1 in most of its cars. Stator cooling channels moved from the electrical steel into the cheaper die-cast aluminum housing, and the electric oil pump Tesla uses elsewhere was replaced with a mechanical one. The inverter’s circuit board works at 12 or 48 volts. The team also said an in-house lubricant change later this year cuts gear mesh losses by 7%.
The inverter also powers the thermal system through a small junction box, so no separate high-voltage line runs from the pack. The thermal module, Tesla’s third-generation heat pump, moves most of its complexity to the coolant side. The compressor bolts straight to the refrigerant manifold with no refrigerant hoses. The module is built, filled, and leak-tested before it goes in the car, and the drive inverter can be serviced from above once the thermal module is lifted out.
Those choices feed the efficiency numbers we covered in how efficient the Cybercab is.
Built for 500,000 miles
The team said the Cybercab is designed to run at least half a million miles, and that replacing a pack before then would hurt its cost per mile. That explains the serviceable pack, the top-access inverter, and the coolant-side thermal system. When Munro asked to buy one for a teardown, the answer was not yet. For now, see whether you can buy a Tesla Cybercab.