I live in a major city and we have freeway closures due to vehicle fires on a near daily basis. Most recently a truck full of bread caught on fire and resulted in one of the cities most major arteries being closed both ways for 4+ hours.
This data is valuable but also slightly I'll-fitted for this purpose.
How many relatively recently sold modern gasoline vehicles in a similar category to the Tesla catch on fire? That's the proper number for the comparison.
(source for delivery stats: http://my.teslamotors.com/forum/forums/tesla-delivers-10030-... source for billion miles http://www.engadget.com/2015/06/23/tesla-model-s-owners-driv... )