Yes I agree that SS has lots of benefits. There was some commentary from Franz that they were able to redesign the body to take advantage of the SS exterior, but overall I'm still not seeing any evidence of weight savings.
Curb weight of the cybertruck AWD is ~6600 lbs vs. ~5000lbs for an F150 Supercrew 4x4 V8
The F150 Lighting with extended battery is 6400 to 6900lbs depending on trim level
Won't matter very much if they can get production ramped and battery performance up 15%
Comparing to ICE truck is not fair because the battery mass makes a big difference. This is evidenced by the F-150 Lightning weighing about 35% more than the ICE equivalent.
Also, the weight efficiency of a stressed-skin design does not necessarily result in overall weight savings, because there are so many variables. It is an exercise in futility to estimate without more information. What it does for sure is free up mass budget for making design trades. Tesla included several CT design features that should save mass, but then added other features that add mass.
Here are some examples of trades Tesla engineers chose for CT that cost extra mass vs the Lightning and Rivian:
1) At the delivery event, it was revealed that the CT has more torsional rigidity than a McLaren P1. Traditional ladder-frame trucks are nowhere close to this. Combined with air suspension, this should majorly improve handling both on and off road, and especially while towing and hauling heavy loads.
2) Almost double the motor power (vs Lightning, but matches top-trim quadmotor Rivian)
3) Rated to tow, haul and pull substantially more
4) Rear-wheel steering and all the accompanying hardware
5) Sturdy (heavy) glass
6) Superior crash safety (I speculate)
7) 5 inches more bed length
Tesla could have saved mass by reducing these key performance metrics. Instead, they apparently decided to design a tough, high-performing beast that comes in line with the competition on mass and length/width/height. Only a teardown and system analysis like Munro & Associates will do can give us a clear picture of how much the design overall was mass-efficient.
But the cargo/hauling capacity does not appear to actually be better than similar sized non-SS-exo trucks. The production cargo capacity is 1000 lbs less than the 2019 announcement, and towing max is 3000 lbs less.
What numbers are you looking at?
Cybertruck is rated to tow 11000 lbs and haul 2500 lbs. It's not as good as the original plan, but still market-leading in its class.
Below are the specs for F-150 Lightning. Even the maxed-out trim for towing only does 10000 and the maxed trim for hauling is 2235, and you can't get both in the same truck.
The Rivian tows up to 11000, but hauls only 1764, despite weighing more than CT and being smaller.