What they are doing is most definitely political speech and is thus protected by the first amendment.
This is so funny. I could not stop laughing. I am going to modify my 1995 Ford F250 diesel.
Probably true if all they were doing is speaking. But don't forget, in this lawless administration, polluting the air trumps probably the first amendment. After all, they enforce the laws they want to enforce and ignore the rest.
It'll be interesting to see what comes of this, now that it's received a bit of publicity.