The relevant metric here seems to be 'miles between fire events'. On this metric, we have exactly 1 data point for Tesla. I would hardly call that "probably enough".

Of course, I'm exaggerating in the other direction. What we really should be calculating is the odds that Teslas burst into flames less often than the average car, given that the average car does so every 20 million miles and the first such event in a Tesla was at the 100 million-mile mark. We're still failing to account for the fact that the average Tesla is newer and probably better-kept than the average car, but it would at least be a reasonable start.

I don't know enough statistics to perform this calculation, but I would like to see how it is done.