HB-1815 passed in 2007 covers having a weapon in a vehicle...
A person commits an offense if the person [he] intentionally, knowingly, or recklessly carries on or about his or her person a handgun, illegal knife, or club if the person is not:
(1)on the person's own premises or premises under the person's control; or
(2)inside of or directly en route to a motor vehicle that is owned by the person or under the person's control.
Also, further down it covers the part about It cannot be in plain view, plus one cannot be involved in criminal activity, etc..
I believe this additional bill was brought about by the illegal confiscation of guns of drivers going through Houston.
What you posted above is correct, but was already posted at least twice in this thread. TXI covered it a few posts ago. This law however does not make your car an extensionof your home, which was I believe what was the statement that was being questioned.
Regardless, 2007 was a good year as it ridded us of that horrible "traveling" clause in the law.