Humans also have a vestibular system[1] and proprioception[2], which I think are very important in making judgments about safe following distance, car handling, and road conditions, in particular in adverse conditions like strong side winds and slippery or icy roads, which may not always be visually obvious.

While some of this can be handled by an IMU, I think humans still have a strong advantage in fusing their various sensory inputs, thanks to millions of years of evolution.

[1] https://en.wikipedia.org/wiki/Vestibular_system

[2] https://en.wikipedia.org/wiki/Proprioception