It's not limited to Infiniti G drivers. I think the vast majority of 18-35 year old drivers in cars like the G35/G37, 335i, IS350, C350, S4, BMW M/Merc AMG are terrible drivers.
They're overly aggressive. They tailgate often. They're often speeding 10-15 MPH over the limit. They constantly change lanes to try and "get ahead" even in the midst of heavy traffic.
I'm no different, by the way. I used to be an awful driver during my early 20s. I think you mellow out over the years, though. I usually cruise in the slow lane these days.