The cars certainly don’t measure the traction, not even once per second. You need wheel slip to do that, and constant wheel slip is not a good driving mode. Not

The cars certainly don’t measure the traction, not even once per second. You need wheel slip to do that, and constant wheel slip is not a good driving mode. Not to mention the difference between static and dynamic friction. At most cars can collect the lower bound of friction coefficient when braking/accelerating and lower/upper bounds when wheels are slipping. If you have a straight stretch of road, and no cars tried to brake/accelerate on that, the only friction data you would have is ‘no wheel slip at .02g acceleration/deceleration’. It doesn’t help the AI predict its braking distance for an emergency braking maneuver when driving that stretch of road, so a conservative AI would be forced to keep a much larger headway than a typical (or even cautious) human.