believe none of what you hear and even less of what you read
"Well, I have always been told it is not legal and you are not allowed, and that it's not a company thing." sanzo87
So who told you this fable? And what makes them knowledgeable on the issue? Surely it not the first time someone told you something that was proven incorrect at a latter time.
I would expect the issue of firearms in DOT registered vehicles would at least have a paragraph in the CDL licensing manuals. I've never read any such statements. That does not provide definitive proof of the regs but it certainly says they do not cover the issue in basic CDL testing.
I'll point out a great example: here on this board you constantly see posting over shipping a handgun using the USPS. It pretty clear that a person can not mail any handgun using the USPS. There are a limited number of exceptions for C&R transactions. No matter how many times the issue comes up someone will always claim everyone is wrong that you can mail a pistol with no reservations on to whom or what type of pistol.