During a 2019 launch event for Tesla's Cybertruck, Elon Musk stood in front of two Armor Glass windows, the webbed lines of shattered glass spreading from an impact point on the not-so- shatterproof glass. Though Musk had an explanation for the failed test, alleging that the glass had already been put under too much pressure, it made it easier to question any current claims about the truck. For example, at the same event, the Tesla CEO confirmed the Cybertruck would be covered in 3mm of the same 301 stainless steel used in SpaceX's Starship craft, essentially making it bulletproof to 9mm rounds.
Though Musk noted the bullet resistance of the Cybertruck, none of the vehicle's official marketing materials mention this feature. The landing page for the truck speaks of the "ultra-hard stainless-steel exoskeleton," but falls short of describing its resilience to firearms. Instead, it simply mentions the ability to "reduce dents, damage and long-term corrosion." Since Musk's mention of the Cybertruck's ability to stand up to 9 m rounds, though, there's been ample speculation as to the resilience of the exoskeleton.
The short answer as to whether the Cybertruck is bulletproof is "kind of." At the 2023 delivery event, Musk showcased a quick video of the truck being pelted with bullets from a Thompson submachine gun, which failed to penetrate the exoskeleton. Musk even confirmed the test on Twitter, though it's possible he wasn't being fully forthcoming, leaving the full extent of the truck's resilience as questionable.