Ergodyne

I want to have mostly a sq based system, but i still want to be able to feel some bass. I want to run 8's just to conserve some space. How well do these hit low frequencies. I mostly listen to mostly rock and R&B so i kind of need some all around performers. I can imagine they will get pretty loud in a truck, but does anyone run these in a car? If so throw me some info. I'm still not sure if i want to run 2 or 3 though. The Vehicle in question is a 2004 POntiac Grand Prix.