Blame the lightbulb so you can sue BMW.
They ARE lawyers after all!
But kidding aside, even *IF* there was ethylene glycol liquid ON the CAT, ANDIF there was a (magically) explosive or flammable mixture of ethylene glycol vapour in the air under the vehicle ... I doubt seriously that would be a hot enough flame front to ignite other car parts et al. It doesn’t add up.
Plus, how does the radiator fluid flow out and UP to the lightbulb housing AND get inside it. These housing are specifically (German) engineered to keep liquids and vapors OUT to prolong bulb life.
Still doesn’t add up.
BTW, do you know the explosive limits of E-glycol vapour (open air, not closed container)? In other words, *COULD* E-glycol form an explosive or flammable mixture in the air under/around/in a vehicle?
Remember, when it comes to perfect seals 90% of the German submarine fleet personnel were killed in WWII ~ and usually by nothing more complex than an oil drum filled with dynamite and a proximity fuse driven detonation system.
So much for the Germans.
What I'd like to focus on is the condition of the car before the "explosion" bounced the car in the air!
That's where the answer to our question of why she didn't get out of the car is going to be answered.
In the Wiki article about ethylene glycol (coolant/antifreeze) the ONLY automotive manufacturer named is BMW.
Of particular interest BMW has sought, almost alone, to make the existing catalytic converters more efficient. They used the highly risky ELECTRIC HEATING COIL or "RING" technology. That's the one you can use on gasoline anyway ~ just heat it up before mixing and it will mix better (discovered during WWII as a way to enable planes to fly higher where gasoline has difficulty evaporating due to the low temperatures).
So, anyway, it's risky enough to put a hot ring in the presence gasoline that it's not done for general use automobiles (like the ones we drive). But here we find that BMW used that technology to HEAT the catalytic converter, also full of flammable and explosive gases, so that it could "start"earlier than ordinary non heated catalytic converters.
(NOTE: current technological advances suggest that low temperature conversion is now possible).
Given the idea that she managed to punch a hole in her radiator, we then know that she spilled HOT antifreeze under pressure out underneath the vehicle. It must have gone everywhere, and it was hot, and it evaporated ~ with the volatile distillates being freed to just kinda' linger around under the vehicle, in the vehicle, in the garage, etc. It was just there everywhere ~ with a 711 degree F "autoignition" temperature ~ all it needed was the presence of that much heat and BANG.
Well, things went BANG shortly after she turned the ignition switch and started heating that Catalytic Converter.
That would have ignited all the volatiles in the garage, under her vehicle, inside her vehicle ~ and there you have it, a simple suffocation ~
You don't need anything but a BMW and coolant to pull this one off ~ oh, yeah, and a work bench to smack into on your way into the garage.
The ATF guys probably filled out a preliminary accident form used for federal employees due to the wife's former employment and her husband's current employment. There'd be a note somewhere in there about the catalytic converter ~ be interesting to see what it says.
Angela Merkel probably got called on this one!