Man...you guys are killing me here. I really don't agree with telling someone to not get better speakers because they love loud bass so they'll go to waste. Would you tell someone to not buy a sub stage capable of big numbers if they'll only turn it up once in a blue moon?
Until we have car audio products shipping with engineering data sheets, we have to live with exaggerated specifications for power handling. Even so, there is always a need for the knowledge of proper system design, and part of that is figuring out how to properly power speakers for long life and great performance. Some of the good manufacturers publish recommendations for setting gains, speaker placement, and so on.