When I have a choice, I travel with the tv/monitor face down on a soft moving blanket. (The blanket to protect against scratches on the glass). You can also sit facing a seat and belt them in, but I prefer Level42's way...It's a little more idiot proof, plus it takes extra stress away from the weakes point of the entire set...The neck.
IF the tv was rattling around enough, I guess I could see the little circuit board attached to the neck vibrating enough that it MIGHT break the end off the tube...But I've transported literally hunderes to tv's and monitors unboxed, and have never seen it.
And frankly, to actually feel a draft from a broken tube, it must've snapped clean off, a small crack wouldn't move enough air from a 14" tube for you to feel anything, especially from the back of the car.
i didn't know it was damaged until the owner told me about it. it was fixed locally but a slight discoloration remained on the screen.
This just stikes me as odd. Whenever I've broken the vacuum on a tube, I can usually see some indication on the fron to of the tube...But I guess anything is possible. However, fixing it requires an entirely new picture tube...If there is discoloration, and the tube has been replaced, I'd go back to that repair shop and find out what's up...Cause it's certainly not fixed right.
Frankly, I'd say if you did manage to break the tube, it was probably just a stroke of bad luck.