Looking At some pictures and diagrams of the Model S battery pack, yes, it does look to be about twice as large as the average fuel tank. HOWEVER, that leaves

Looking At some pictures and diagrams of the Model S battery pack, yes, it does look to be about twice as large as the average fuel tank. HOWEVER, that leaves out some really interesting things to note. First of all, most automotive gas tanks are made out of ~1/8" HDPE. While it has decent cut and abrasion resistance, it's of virtually no use when trying to combat punctures and is also pretty flimsy, leading to deformation and possible cracking during an accident. While, yes, a punctured battery pack is guaranteed to ignite while a gas tank is not, that is also the only way for the pack to ignite. An object has to physically pass through the battery pack, while a gas tank could potentially start a fire if it cracks and starts leaking. There's a reason why you're supposed to try to get out your car as quickly as possible in case of a crash: fuel leaks very easily. In comparison, batteries are much more impact resistant due to their more solid state nature. Also, it seems that whatever struck the car seemed to hit under or very close to where the front passengers sit. Had that armored battery pack not been there, there's a very real possibility that the driver would have been impaled. With that in mind, it should be pretty clear that this was a freak accident and not really representative of the average car crash.