All or nothing
The only way I see this working (in all honesty) is for it to be universal, and immediate. IE: December 31st 20XX - any driver worth his salt heads out on their last chance power drive on the road to nowhere.
January 1st 20XX+1 - all cars are controlled by computer: NO humans involved whatsoever. All liability is now in the hands (brains?) of the corporations who are legally held responsible for every life on the roads .
It's the only way that it could work - human drivers are too unpredictable for software to keep up with - especially if it has to 'phone home' whenever it comes across a previously un-anticipated situation.