In the near future, the world is falling apart. A disillusioned highway cop turns vigilante when his young family are slaughtered by a motor cycle gang who refuses to recognise the law.

I like your adjustments, and you are right, except i'm not sure about the "futuristic motorcycle gang". To me that implies the gang rather than the film is set in the future.

And it spawned 2 sequels. And the franchise has been rebooted: "Mad Max: Fury Road" is scheduled to be released in 2015.

And it spawned 2 sequels. And the franchise has been rebooted: "Mad Max: Fury Road" is scheduled to be released in 2015.