After two years of trying to do the impossible in first turning around and then saving Chrysler for Cerberus, ex-CEO Bob Nardelli has apparently returned to the investment firm that recruited him in 2007.  Nardelli’s new role will be heading up Cerberus’ unit charged with overseeing the operations of the investment firm’s portfolio holdings, appropriately named Cerberus Operating and Advisory Company LLC or COAC.  Nardelli will manage other operating pros responsible for monitoring and assisting Cerberus’ current investments, as well as sourcing and conducting due diligence on new opportunities.  Cerberus hasn’t shown much of an appetite lately for making new acquisitions, but there must be a few companies amongst the private equity firm’s 30 odd portfolio roster that can benefit from Nardelli’s brief education in the auto industry.