It's not the pitch that is the concern, so much as the "shape" of the sound.

Panels can be turned into incredibly good speakers (example) but that's when they are flat. The surfaces in a car are going to created much more complex wave-fronts because they aren't flat.

I presume that what LG is showing off is some sort of system that compensates for this. I wouldn't be perfect, but it could potentially be good enough to improve on the speakers you can otherwise get in cars.

Of course, 17 year olds will use it to vibrate the rivets out of their cars because that's what they do.