Not my-neighbors-know-I'm-on-my-way-home-when-I-turn-the-corner-a-mile-up-the-road.

Your perception of subwoofers is being clouded by those who abuse them.

When you hear someone coming from a mile away because his stereo is booming, not only is he making the music sound terrible inside his vehicle, but he's doing it with insane amounts of amplification and multiple subwoofers.

That's not the kind of sub I'm talking about. I'm not talking about multiple sets of bandpass 12" push-pull subs in the open back of a slammed pickup truck.

I mean a single 10" sub, preferably in a sealed enclosure, tuned so that it only gently fills in the low frequencies with a nice, dry, flat, non-boomy response. A sound that is no more audible outside the vehicle than the regular speakers. A properly installed and tuned sub is as "transparent" as the regular speakers.

On my car, you can't hear me coming down the street any sooner than you would if I didn't have a subwoofer. The only difference is that when I get close enough so you can hear me, you hear a nice pleasing frequency response that includes the correct amount of bass.