GM has recently filed 3 different patents, which seem to be for new active aerodynamic elements. We could very well see these featured on the upcoming C8. The three patents include active side skirts, active spoilers and downforce generating ducts. By intelligently controlling how the air moves across and through the vehicle, they can efficiently boost the performance of their upcoming models in all environments. GM seems to finally be following what has been used on Italian exotic models over the past few years.
Oddly enough it looks as though 2020 911's will also be using similar active aero tech. Unfortunately I feel like these kinds of features are more a result of tightening EPA restrictions, rather than a pursuit of maximizing performance.
Part of this needs to play into how the engine is being cooled. Cars like the LFA have a lot of focus on efficiency and they have stood the test of time. Some design might be ugly like the LFA vents but they serve a purpose.
Less drag coefficient is a benefit to everyone, and I'm not all that surprised to hear that Porsche is going the same route with their next gen 911. The competition is fierce in this segment and every automaker is looking for ways to improve.
While we don't know a lot about the C8's underpinnings, I think its pretty likely that GM will be going with lightweight materials. There's a good chance we will see an aluminum spaceframe and a fiberglass body, with carbon fiber accents.