Further conjecture: I am not familiar with the architecture of modern vehicles, but I know (hackable) software has been increasingly at the center of these. Failing that, there's always (easier to detect) hardware tampering. Fortunately, if things burn you destroy the evidence, and with the frequency of automobile accidents there is little motivation for an average investigation to turn micro-forensic... particularly with a young person in a risky age group in a foreign country.
Of course, maybe he just did a fat fifty lines of coke, or a hit of meth? Or, just maybe, he was challenged to a one-man street race after a dose of Scopolamine: http://watchdocumentary.org/watch/worlds-scariest-drug-video...
Non-conjecture: There's loads of ways to off people, and the military industrial complex makes it a business. This guy forced a general from that complex to end his career, later visited his country and wound up dead early in the morning.