DaveKillens wrote:...it appears a coat of light silver or grey is better at reflecting the heat back and away from the bodywork.
Why would you want to reflect the heat back to the source? Besides, the vents and natural contained airflow do their job of channeling the heat towards the rear.
Although if you think about it the visible gray area on the Mercedes doesn't even deal with heat, as it is in front of the radiators and the top part is around the intake.
I also go with the guess of painted CF, but for the sake of the attention to detail.