In the trunk, where spare tire is.
The 2004 BMW X3 has double overhead cam (DOHC).
The 2010 BMW X3 has double overhead cam (DOHC).
The 2009 BMW X3 has double overhead cam (DOHC).
The 2006 BMW X3 has double overhead cam (DOHC).
The 2008 BMW X3 has double overhead cam (DOHC).
The 2007 BMW X3 has double overhead cam (DOHC).
The 2013 BMW X3 has double overhead cam (DOHC).
The 2012 BMW X3 has double overhead cam (DOHC).
The 2011 BMW X3 has double overhead cam (DOHC).
The 2005 BMW X3 has double overhead cam (DOHC).
The 2014 BMW X3 has double overhead cam (DOHC).