The standard sound system on all X3s include 8 speakers and 2 subwoofers under the front seats. So yes, even the base sound sys on the X3 is better than the one in the X5. However, I do think that it's only acceptable and wish we had the premium sound system, and the regular sound system lacks clarity sometimes.

That said, my friend has an X5 3.0i and wishes he had my subwoofers. (I wish for his engine)