Don’t know the answer to that. From what I understand it’s pretty difficult though — a lot of the new electric vehicles come ‘autonomy-ready’ but I am guessing that’s possible because they are basically giant computers on wheels. That said, even if you could retrofit combustion cars with autonomy systems, why would you? They’d still be more expensive to run. And the whole appeal of the combustion vehicle is the ability to drive it, so the people who do retain them for romantic reasons will probably still want access to the steering wheel.