Cost an extra $700 for this option on Infiniti based cars

Here are a couple of sites that explain what it is and does:

http://nissan-global.com/EN/TECHNOLOGY/INTRODUCTION/DETAILS/4WAS/index.html

http://en.wikipedia.org/wiki/HICAS

Supposedly, it helps with stability at high speed and enhances power steering at low speeds. l bought a fully loaded 07 G35S with out the Active Steer option. l heard it takes away from the feel of driving a sportscar like the G35 so l opted not to get it.

If you like a sports car feel then you may not want this.