Cars crash. Expensive cars crash. Cars catch fire after they crash (certainly not in the majority of cases, but it does happen). I'm a Firefighter/EMT in a department that covers a reasonably affluent area. The vehicle Mr. Hastings was driving would not be unusual around here (and vehicles like it would not be unusual to see in the wrecks we respond to).

Your suggestion that somehow being a late model Mercedes makes it impervious to collisions is just silly. I could run a report of our wrecks over the last year, but I'm sure there have been at least a dozen that involve late model cars like the one in question (from various manufacturers). Two of those included at least one fatality. None of them caught fire (but given the small sample size, that's not surprising, over the last decade I'd guess something like 1 in 50 wrecks I've seen involved a post-crash fire).

Regarding the explosion... I've seen nothing that indicates to me that there was an explosion. People described a loud noise (crashes are loud), and a fire. The video of that fire is completely consistent with a post-crash vehicle fire.