It has only been a short few years that you could carry a handgun legally in your vehicle in Texas. However for years if you were traveling out of your county for over night you could as well. But the carrying legally in the vehicle is new in Texas and I am pretty sure that it is intertwined with the Castle Doctrine laws. Again I have never read or heard of a citizen that is legally allowed to own firearms(in Texas) that is in a justifiable shooting and is cleared by a Grand Jury of the shooting ever being charged with illegally carrying the firearm. Somewhere here perhaps,but I have honestly never heard of it.