[aerohead]

In the March,2013 Motor Trend article on the new Stingray,they comment on the improved adhesion of air to the bodywork due to the new backlight based upon the Corvette Racing Team car,and how it improved the upkick spoiler performance.
The contour of the roofline is extremely close to the 'Template'-II and the 'stock' upkick would actually aggravate airflow.
The SEMA,Bob's Big Boy
'outside' serving tray spoiler would create less drag for the downforce created,low base pressure of the wake acting on the underside of the shelf's moment arm,and also allowing the air to leave parallel to the road,a feature favored in racing for decades.