SpaceX the most successful company doing by far the most launches, is producing about 1 new Falcon 9 Upper Stage about 2x a week at most.
A successful car is produced 5000x a week, maybe even 10000x. That gives you real cost savings, but 1-2 is really just serial production. That does give some savings but nothing like automotive.
So any small rocket company that talks about improving launch cost by mass production and talking about 'using methods from the automotive industry' is just delusional. Even if the were spectacularly successful and the was actual demand (there isn't) and launching as often as SpaceX.
The cost saving from mass production would still be really quite small. Going from the price of your first rocket to say 100 every year saves money, but nowhere near as much as reuse does.
RocketLab the only company that actually launches small sat regularly was absolutely convinced mass production was the way to go and then the CEO literally eat a hat and pivoted to making the rocket reusable instead. But somehow the we gone make small launch cheap with mass production story still convinces some investors.
Edit: Prat of why I mention this is just recently I was listening to interview with the CEO of Augsburg Rocket Factory from Germany and they made that argument again.