Google's self-driving cars have gone 300,000 miles without an accident. That's somewhere in the neighborhood of 30–42 average-teen-driver-years worth of driving. Statistically, about 1 in five teenagers reports having an accident in any given year. So we would expect that the same number of miles driven by teenagers would have resulted in, on average, 6–8 accidents—more if we're talking about teenagers in their first year of driving.
In other words, Google's self-driving cars are already at least an order of magnitude safer than teen drivers. That's probably a statistically significant difference.