If we have a mix of human drivers and AI assisted drivers on the road, nothing short of AGI is going to be sufficient. Aspects of driving involve theory of mind - anticipating what another driver might do, sometime eye contact, etc.

An alternative solution would be to allow only autonomous vehicles and have these vehicles in a mesh network so can coordinate to drive efficiently and avoid mishaps. This would work reasonably on highways, but on local roads with pedestrians, bicyclists, and unexpected obstructions, theory of mind and ability to handle outliers will be important.

My conclusion is that something close to AGI would be required to implement succesfully.