I leave it about 50% of the time when my car is parked, and it is impractical to bring it with me. This is the case here (you need to add foam padding):
http://www.aboveroute.com/cgi-bin/s/s1_jump_to.pl?m_id=27&to_url=http%3A%2F%2Fwww.officemax.com%2Fmax%2Fsolutions%2Fproduct%2FprodBlock.jsp%3FBV_UseBVCookie%3Dno%26expansionOID%3D-536879615%26prodBlockOID%3D55119
And I use a chain to lock the case to the car body in the trunk out of sight. And when I'm home, I bring the safe in with me. Yes, I'm paranoid...