When famous people die unexpectedly, there is often a conspiracy theory to follow. Hastings was speeding, he had drugs in his system and the tree he ran into was a sturdy one that wouldn't have been knocked down easily despite what some of the people who believe the conspiracy have said. Also there is no forensic evidence at the site of a bomb.
Although conspiracy theories can be fun, and some have proved true with time, Michael Hastings' death was simply a tragic car accident. Although he was paranoid before his death, there is no evidence of fact to back up the paranoia. Hastings was working on three or four different stories, none of which looked like a motive to have him targeted for death.