Interesting low profile rear wing extension on a 2014 Corvette Stingray
 

The 2014 Chevy Stingray in SEMA, biggest aftermarket trade show, had a rear wing concept that probably had less to do with additional downforce but to extend and have a cleaner rear flow. Ecomodders have suggested and sketched out these kinds of extensions/rear wings. Maybe aftermarket wing makers could finally produce this type of aero-wing for a larger selection of cars. Chevrolet Corvette Gran Turismo 6 Concept: Live From SEMA

looks just like the one i built for mine:
Image: Chevrolet Corvette Stingray Gran Turismo Concept, 2013 SEMA Show, size: 1024 x 682, type: gif, posted on: November 5, 2013, 7:37 pm - MotorAuthority

That is actually what I call an "air slot".

I have one on the roof of my pick-up truck, and can also be found on the rear roof edge of SUV's and econoboxes alike.

The slot, in theory allows some of the high pressure air above to escape downward, which draws the rest of the flow above it down too (to fill the void).

The low pressure area will tend to concentrate around the underside of that protrusion. Not a big follower of drag racing, but I believe its funny cars that use that same type, or maybe pro-stock. At lower speeds it decreases drag but increases downforce at higher speeds. Not as much as a wing though.

wing
 

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.