That leaves approximately 227,250 fires since the Tesla has been introduced, of which Teslas are known to be responsible for three. Or 0.000013% of all car fires in the relevant time.

That said, the other test might be more relevant, as there were more actual Teslas on the road in the past 140 days, rather than at day zero of launch. I don't have the figures to calculate, say, fires/#miles driven.