The statistic is greater that 250,000 car fires per year.
I was trying to be conservative, although the numbers that are out there are between 150,000 and 200,000. Not sure where you are getting that 250,000 number from.
What I was trying to point out, maybe not in the most direct way, was that all these statistics I have seen are flawed (mileage driven, number of cars). Not very relevant. The only number that counts is fires per collision and since MS drivers are expected to drive a bit faster than the average car out there, speed also needs to be factored in, to some extend. What I meant to say is nicely summarized here:
Tesla's Fires: What Are Some Potential Long-term Ramifications? - Forbes