It's doable.
L
Perhaps an incindenary device was remotely set off in the car cabin while she was driving. Or she stopped by the road and was pushed further off. For some reason she was unconscious--and the cabin was then torched.
Those are a few ideas I have. The stories generally read, as I assumed, that she hit a "pole" next to the road, like a traffic light. Untrue.
Simpler and less traceable bound and fed a breathing mixture rich in Carbon monoxide. When unconcious the fire deatroys the body and removes any and all traces of restraints.
Vey doable
Stay well - stay safe - Stay armed - Yorktown