Make it a true fastback. Use different rear sheetmetal for the Convertible. The current car uses the same trunk to save costs...but you'll make money back in the first 2 years if you go the same route as the 64-73 model years that had distinct rear sytling from both fastback and vert. Trust me. And add the pedestal mirrors ala 2013 Fusion/MKZ. They cost a little more but look sweet and look to Porsche to see how they did it without adding extra glass to fill the void. And one more thing... loose the triangle (Dorito) rear window and have a pillarless b-pillar.