No, spontaneous vehicular combustion. (Forgive me if this joke was used, I haven't read all the replies yet!) :-)
It was just a coincidence that one of the Arabs had a tour badge from the WTC on 9-5 and left NYC on 9-11 and sold this woman the car (providing him with access to a duplicate key).
When this is over we'll learn that it was a delayed part of a suicide pact with the scientist to fell/didn't "jump" from the bridge in Tennessee.
How common is it for the interior only to burn completely in a car accident? Could a dropped cigarette do the job that completely? Doesn't seem like an engine fire and the gas tank did not ignite.
The car fires I've driven by in my life did not appear to be fatalities (generally a single vehicle pulled over to the shoulder), some of these starting with the engine on fire.