Driving in excess of 40mph is not the proper way to execute a moving vehicle photo shoot. This was our only makeshift method to get the motion blur as we were driving on the Pacific Coast Highway by Los Angeles, CA. This also happens to be my first attempt at a moving vehicle shoot, with my brother on the Harley, his wife driving the chase car, with my 1D strap wrapped tightly around my arm hanging out the window, shutter activated by the wired remote, and communicating over a Bluetooth headset.
Without a neutral density filter, I was forced to shoot at ISO 50, f/9.5 at 1/90s with my Canon 16-35mm. There is obviously some major post processing and composites for the visual effects, but the motion blur is real. The overcast sky made it easier to get a softly lit image.