In the latest Porsche 911 Secrets episode, Dieter Landenberger, the Porsche Museum’s Chief of Archive takes a closer look at a 1984 aerodynamic prototype which was equipped with a new front spoiler, covered wheels and a modified rear wing.
Not very big changes, but as a result the prototype had a drag coefficient of 0.27 which was significantly less than the standard 911 at the time, which had a drag coefficient of 0.40. In comparison the current generation 911 (991 series) retains a drag coefficient of 0.29.
The all-new BMW i8 has a drag coefficient 0.26, while the McLaren P1 supercar has a drag coefficient of 0.34, while generating up to 600kg of downforce (5x more than the discontinued MP4-12C).
Obviously the prototype of this 911 never went into production, but many of the aerodynamic updates made it into road-going models.