Oh, No!

I will give you 0.1%, given that there has been one fire so far due to an accident, even if it was some drunk moron running his S into a concrete barrier. But this is not about accidents, it is about common road hazards: receiver hitches, tire irons, rebar, pretty much any random piece of steel longer than a few inches. Fuel tank punctures from road hazards in a typical car are extremely rare due to being in the back of the vehicle and sitting higher off the ground as compared to the body pan and suspension. Tank punctures only happen in accidents, and I will gladly attest to how sphincter-loosening-scary that is. But, again, this is about road hazards. The worst case for an ICE from road hazard is generally getting a hole in the oil pan or transmission pan/case, but it doesn't happen very often due to the small target size and the fact that they sit a little higher than the suspension and frame. Regardless, if such does happen to an ICE, it does not result in a total loss fire, whereas at the moment, such is almost guaranteed with the Model S pack.

The surest way for Tesla to kill their brand is to deny that there is a problem. But, on the other hand, when there are 1-2 road hazard fires a week a year from now, given the incident rate (~every 50 million miles) and production rate, these won't be newsworthy.

 

An ICE may not be lost in a fire, but the loss of fluid to the engine or transmission at highway speed can be enough to total a car. While they are smaller targets, they are substantially thinner than an S's battery tray.

A fire is worse, but no one was injured in one, and they had as much time as a car with a pierced oil pan to get over and get out. By design. The insurance rates on the Tesla S might go up because of this, but it is far from evidence of a problem.

There still isn't any evidence of it being ordinary road debris or not. Since it doesn't go beyond a flinch in surprise or an "aww, f-", we have no idea how many road debris the Teslas on road have collided with without anything more than scraped bumpers and under sides. Six inches will roll over most things seen as debris on the road.

This is another tidbit from one of my links:
" The majority (75%) of highway vehicle fires are caused by mechanical failures or other car malfunctions. However, vehicle fires caused by collisions are responsible for almost 60% of vehicle fire deaths."

Three quarters of liquid fueled vehicle fires aren't the result of an accident. How many Teslas have caught fire from a design or production error?

 

The true bottom line is vehicle safety. And the Model S is the safest car out there. Tesla has shown itself to be an innovative and responsive company, and you can be sure they are analyzing these fire incidents to determine if there is anything they can do to make them less likely. The NHTSA determined in its study of the first incident that there was no defect or design flaw in the car.

Which would you rather have: a car that catches fire three times as often, or a car that is three times more likely to kill you? I don't believe the S is three times as likely to catch fire, but focusing narrowly on what specific kind of incident can result in a fire, rather than your chances of being killed or injured in a given car model, just makes no sense. Fire hazard is one of a thousand things that a responsible car maker works to minimize in designing a car. But when buying a car it makes no sense to emphasize one specific type of hazard over and above the overall safety of the car.

If it turns out that the armor plating under the battery pack is truly a weak point, you can be sure Tesla will improve it in future model years. For now, your overall chances of being killed in a Model S are still less than in any other car. (Of course, people still drive VW Bugs and GM cars, so, clearly, not everyone makes safety their first priority in choosing a car.)

 

Most people that drive bugs and gm's probably can't afford the $80k asking price for one. Considering that is half of what I paid for my house I will stick to driving the ticking time bomb that is my Prius. For now...

 

...what is unique about Li batteries is organic-complex electrolyte which is flammable. Most other batteries have inorganic electrolyte (eg; H2SO4 lead acid battery).

Here is good explanation, root cause sounds like spark+air or everheating (apparently not pyrophoric- but I give you huge credit for knowing that word!)
HowStuffWorks "What is causing lithium-ion laptop batteries to catch fire?"

 

During my truck driving days, I hauled hazmat loads that could wipe out big chunks of real estate. I needed to know what big words like that meant.

 

While the Model S is still a rich person's car, Tesla will be selling a $30,000 car in a few years. As for the Prius, it is an extremely safe car.

 

okay, more than a few years, but they are getting closer