https://www.law.cornell.edu/uscode/text/18/926A
Unless you're talking about intrastate as opposed to interstate. I also never said that you can't have a gun in a commercial vehicle, just that it's federally regulated.
I said that companies prohibit you from doing so.
That isn't applicable if you have a LTCH and it's honored in your location. Otherwise, how do you legally carry your handgun in your car?