Does it matter how long it takes? Doesn't just total output matter?
Heck, "throw more servers at it" has been an accepted practice. Who cares if it takes 30 hours as opposed to 10 if you can have 3x the number of cars under construction at one time.
Heck, "throw more servers at it" has been an accepted practice. Who cares if it takes 30 hours as opposed to 10 if you can have 3x the number of cars under construction at one time.
Additionally a plant that takes 30 hours per car is typically going to have less output than a plant that takes 10 hours per car. Typically each minute during production the car is taking up space, being worked on humans or robots, etc. Additionally efficiencies favor shorter pipelines. Generally a 10 hour pipeline is physically shorter than a 30 hour. Parts, staff, troubleshooting etc is easier on a smaller pipeline. Additionally having each car bridge 4 working shifts for the workers has overheads of it's own compared to 1-2 shifts. Doubly so if you are trying to iterate quickly.
Imagine an assembly line moving at 0.5 mph, for the same physical foot print you could have 3 lines that are 10 hours each instead of a single line that runs for 30 hours. Now imagine there's a issue that shuts down a line for an hour, it's better if it's 1/3rd of your capacity down instead of 100%. If you try an improvement, it's better to put 1/3rd of your production capacity at risk instead of 100%.
Also, the whole claim would really need a citation, and careful parsing of the methodology. 3x difference in a mature industry like car assembly is very unlikely, and requires a very strong proof to back that statement up.
The 10% difference pays the next factory.
Some highlights: front 3rd of chassis is one piece, rear 3rd of chassis is one piece, the glass roof is a huge piece and before that's installed things can be installed by robot (steering wheel, dash, seats, etc). Many things are radically simpler, like the interior, dash is basically a aluminum bar the width of the car with an arm for a 15" monitor. Even the ventilation system is simple, few parts, and easy to install. Most cars spend quite a bit of complexity for gauges, displays, buttons, vent controls, temp control, fan control, fans, emergency brake, air valves, etc.
Monroe on youtube (engineer with significant experience, used to work at Ford) took apart an early model 3 and wasn't impressed, didn't recommend it, and called out many details that were expensive, labor intensive, etc. He did a new model 3 and model Y and left quite impressed. Many innovative changes to make things easier to produce, cheap to reduce, reduced parts counts, etc. Monroe claims tesla is iterating their production faster than anyone else he's looked at, and he's looked at a very wide variety of cars (and other products for that matter).
Monroe also reviewed the VW ID.4 and left quite under impressed. Ironically he didn't expect much from the Ford Mach E, but was very pleasantly surprised to see innovative engineering, impressive design, and overall was quite impressed. Although he was horrified by the complexity of the cooling system and has serious doubts about it's long term reliability.
Meanwhile, I assume that space is the cheapest part of the car factory, dwarfed by robotics.
I mean, the VW is cheaper than the 3, so that implies they aren't spending that much more.