Nav Mesh Agent Shake

Hey, I've been experiencing an issue recently with my project when using the Nav Mesh Agent. The car shakes back and forwards constantly while travelling to its destination, I've tried stripping the car of all components (apart from nav agent) to prevent interference from other components, I've tried setting the destination once in the script or multiple times in update, I've tried like 10 different nav mesh build settings for the track and yet nothing seems to work. He travels round the track fine but this shake he does is really noticeable. I've also noticed its not a purely visual thing, if I give him box collider and rigid body and he touches you, he will slam your car across the map with his shake. Finally there is no frame rate issue, I'm constantly above 100fps so its not a stuttering from low frame rate.

Here is a video of the issue: Nav Shake