But you don't know what P(tesla catching fire at 15 years old) is yet. You'll have to wait and sum all the tesla fires from before to N years from now to do a c

But you don't know what P(tesla catching fire at 15 years old) is yet. You'll have to wait and sum all the tesla fires from before to N years from now to do a comparison, where N is the {avg age, or max age, or something more complicated} of the a car in the ICE cohort. That or you can recalculate the "53 fires per billion of miles" statistic, breaking down by cars M years or younger, where M is the {avg age of a tesla, or max age, or something more complicated}