1.7 million miles sounds a little suspicious to me. They would need to have tested something like 17 cars for 100,000 miles each.
I think they have many more than 17 and they are running nearly all day, unlike personal transport.
One thing I wonder is how they will cope up here. Sure, it's fine in summer but those days when you can't see the road at all because of snow? ... well, I hope they don't rely just on seeing road markings.