Sorry, I am too swamped at the moment to do the legwork, but Packing.org will have the direct answer or the direct link to TX laws to read for yourself.
UPDATE: Curiosity got the best of me. GOD BLESS TX!!!
According to the statute, you MAY carry loaded inside the car, and YOU MUST CARRY CONCEALED!!!
You are required to give the officer notice upon a traffic stop (any situation where he would ask for your driver's license), and it is
ILLEGAL TO TRANSPORT A FIREARM OPENLY IN PLAIN VIEW. If you boxed it I'd put the box under the seat. Frankly I'd either keep the weapon in your console or on your person while driving.
§ 46.02. UNLAWFUL CARRYING WEAPONS. (a) A person commits
an offense if he intentionally, knowingly, or recklessly carries on
or about his person a handgun, illegal knife, or club.
(b)
Except as provided by Subsection (c), an offense under
this section is a Class A misdemeanor.
§ 46.15. NONAPPLICABILITY. (a) Sections 46.02 and 46.03
do not apply to:
....
(b)
Section 46.02 does not apply to a person who:
Text of subd. (b)(1) as added by Acts 1997, 75th Leg., ch. 1221,
§ 4
(1) is in the actual discharge of official duties as a
member of the armed forces or state military forces as defined by
Section 431.001, Government Code, or as an employee of a penal
institution who is performing a security function;
Text of subd. (b)(1) as added by Acts 1997, 75th Leg., ch. 1261,
§ 28
(1) is in the actual discharge of official duties as a
member of the armed forces or state military forces as defined by
Section 431.001, Government Code, or as a guard employed by a penal
institution;
(2) is on the person's own premises or premises under
the person's control unless the person is an employee or agent of
the owner of the premises and the person's primary responsibility
is to act in the capacity of a security guard to protect persons or
property, in which event the person must comply with Subdivision
(5);
(3) is traveling;
____________________________________________________________________________________
Text of subsec. (i) as added by Acts 2005, 79th Leg., ch. 288, § 1
(i) For purposes of Subsection (b)(3), a
person is presumed
to be traveling if the person is:
(1)
in a private motor vehicle;
(2) not otherwise engaged in criminal activity, other
than a Class C misdemeanor that is a violation of a law or ordinance
regulating traffic;
(3) not otherwise prohibited by law from possessing a
firearm;
(4) not a member of a criminal street gang, as defined
by Section 71.01; and
(5)
not carrying a handgun in plain view.