In the day, a higher frame rate might help, however, it will make it worse at night.
Also, try maxing out the bit rate.
Another thing you could try, although I don't know what the result will be as I've only used other cameras (photographic, action, dash), is to increase the i frame interval. This should effectively be like increasing the bit rate as the i frame is the full frame from which the other frame are referenced, so is the biggest file. Less i frames might = less compression on the other frames. The downside maybe unforeseen issues with too much change between i frames resulting in the opposite ie larger frames between the i frame actually making the picture more compressed and worse. I'm guessing with that one you'd need to play about and assess the sweet point for picture quality.