I was doing a similar test with my GoPro8 in my Lotus recently. The trick is to lock the exposure at some point outside of the car to avoid the over-exposed image. Which is annoying as you need to do this every time you turn the camera on, and if you have a fixed mount on the engine compartment glass, its hard to reach the camera display. Also, for onboard videos, I recommend turning off the wind-reduction as the sound is then more clear (it seems you have this turned off).