Complex sentence: Rear DVD player was optional on all models as well as a DVD based navigation was optional on all 2003 "Premium", 2004 "Ultimate", For 2005 the navigation was only available with the new "elite package" on the 2005 model year.
Split into simpler sentences: Rear DVD player was optional on all models, as well as a DVD-based navigation was optional on all 2003 Premium and 2004 Ultimate trim levels. The navigation was only available with the new elite package on the 2005 model year.