I had a similar experience with a local Cable company van. Nobody screamed out the window but the 6 inches at 50MPH sounds real familiar (it felt like 3 inches). Thinking about it, someone screaming, showing that it was premeditated would be a little reassuring. I can only assume the idiot that passed me never knew I was there. Vehicles before and after him were giving me 5 feet. I was close to home so I called the company and complained. I got a call back from a supervisor and had to inform him about the 3ft for bicycles law here in AZ. I should have followed up with a letter.