Revealed: Tesla CyberTruck Held Together by Glue

[ProfessorGAC]

12. Close To Accurate

They stainless steel they used (N-304L) is cheaper than 316L or the 20 series, but there are cheaper stainless alloys.
The decision wasn't made strictly for cost.
In fact, they could have used spring steel for the entire unibody for a lot less money.
I saw a site that said the unibody is made of aluminum. More than carbon steel, but cheaper than stainless.
That all said, 300 series stainless was, in fact, a poor choice for the ocean states or the cold weather states where road salt is used.
It still doesn't rust but is susceptible to chloride cracking & subsequently pitting when the cracking gets beyond the microscopic stage. (Which is exponential vs. time as surface area is increased!)
It also explains the glue. Welding stainless to aluminum is a questionable practice, taking VERY high precision, challenging even a robotic welder. 10°F too high at the point of maximum local heat can split the aluminum.
So, while they didn't use a more expensive 20 series, they didn't really use a cheap grade. Still pretty pricey.
But, it was still a foolish choice.