If you have a look at this video from ShelbyFest, the in-car video is a GoPro Hero+, the rear-view camera is one from Repco, Gator HD 1080p. All of the audio is from the Gator, as being mounted at the back hanging below the body it seems it picked up more exhaust and tyre noise and less wind. The audio from the in-car was pretty woeful with too much wind
I guess in your 40 the mic may be less of a problem