I think this bit of trivia ties into the current topic about not just the design of the vehicles, but how Max is portrayed:
Instead of the reboot being a remake of Mad Max (1979), revealing how Max Rockantasky became The Road Warrior, George Miller decided that the reboot will take place in the post-apocalyptic Australia, years after the new Max (Tom Hardy) lost his family, because he did not wish to do a remake or retell the story that had already been told and had wanted to update the universe and the wasteland and wanted new moviegoers to remember Max as a man with nothing to lose after losing his family.
First off, the vehicles are suppose to be over the top because of the world. Miller has stated that he wanted the art direction to be beautiful because anyone who lived in the wasteland would try to make their world with whatever beauty they could find. Not to mention, for the cars, I agree that for Immotan Joe's armada, they're designed to invoke fear AND are his personal branding.
So, basically, it wouldn't have matter if it was Tom Hardy, Mel Gibson or anyone else playing the role of Max, as it was Miller's intention to remind us that Max is someone who is a lost soul who has nothing to really live for except for those moments where he helps people. I mean, Max was a police officer. He used to care and help people before the world went completely nuts. And as Max himself stated in the first film, he tried to leave because he was "worried that (he) would become like (the bikers), a terminal crazy." Him losing his family is pretty much drove him past that line that made him being the human being and a former shell of a man. And that's what we got with
Fury Road. At this point, Max doesn't care about anyone or anything, basically being nothing more than an animal. And it was his interaction with Furiosa, The Wives and Nux that makes him a human being once more, giving him something to actually care about once again (much like how Nux's interaction with Max, Furiosa and The Wives turned him from a run-of-the-mill, suicidal War Boy who was willing to die for Immortan Joe into a person that cared and gave his life for a much better cause: for people he truly cared about) .
The only thing that people miss about
The Road Warrior,
Beyond Thunderdome and
Fury Road is that the whole "pulled into a situation that he doesn't want to be in and the whole thing turns into a big chase scene with Max as the reluctant hero" is Max's last trait from his past life. Those moments end up being necessary for Max, as its the only thing that keeping him from becoming a complete monster like Toecutter, Lord Humungus, Aunty Entity and Immortan Joe. Its those moments of him being a reluctant hero that pretty much gives him a reason to live as well. And at the start of the film, it was one of those moments that lead him to be completely overrun with guilt for failing to help, and Furiosa's cause to help her and the Wives, though not what he wanted to join, ended up becoming his chance at redeeming himself in his own eyes (he probably feels like he's unworthy because he still carries the guilt of not being able to save his wife and son from the first film and the failure of helping those who he has hallucinations of in this film multiplying that guilt). In one of the trailers, he himself states, "I was a Road Warrior looking for a righteous cause." We don't know if he was just saying that as a means of explaining what he was looking for during the events of
Fury Road, or if that line (which I don't know if it was present in the film or not) was meant to explain basically who he has become: just someone looking to help and each event has given him a reason to go on. Essentially, he's forced to face the question, "Are you going to help these people, or are you going to become a completely cold-hearted ******* like everyone else?"
Or at least, that's how I see it. To me, each event is Max's way of remaining a human being in a place and time where humanity is a weakness in the eyes of those who are powerful and prey upon the innocent. He does what he can, and when he messes up, he feels guilt about it. And when everything he has is stripped away, only the cause is the last thing he can hold onto.