Although the complete results of Robb Report’s annual Car of the Year competition will not be revealed until February 24, when the magazine’s March issue hits newsstands, the occasion of Detroit’s 2015 North American International Auto Show—from January 12 through 25—proved the perfect opportunity to announce the Porsche 918 Spyder as Report Report’s 2015 Car of the Year. Detroit—home to Robb Report’s new parent company, the private equity firm Rockbridge Growth Equity—is the industry’s unquestionable focus th…