2 way, 3 way, 4 way?

That's what they WANT you to think, but it is not necessarily true.  2-way, 3-way etc. generally refers to the number of speaker elements included on each side of the stereo set.  2-way means a woofer and a tweeter.  3-way is woofer, tweeter and midrange.  4-way adds a "super tweeter."  5-way usually means two super tweeters.  But generally 4- and 5- way are simply marketing gimmicks.  2-way is the most common and generally the best choice.  3-way systems can in theory be "better" than 2-way, but only if they are well designed and use high-quality components (read: expensive.)  Of the commonly available coaxial speaker systems, stick with 2-way.  If you go component, 3-way can be better if you have the skills to install them properly.

Realize also that if your car has a subwoofer and 2-way mains, then your entire system is a 3-way system.  Etc.