I am running the SPZ60s in my Scion tC and they are definitely a nice sounding speaker.
The rest of my equipment right now includes:
JL Audio HD600/4
Image Dynamics IDQ15 sub sealed
I will be swapping out the SPZ60s in the near future to go 3-way active up front and will be adding a 2nd sub and the proper amps to do all of this.
Also, if you care about sound don't run rear speakers, they just pull your soundstage back.