I recently found these videos on wimp.com, driving around with the camera mounted on the dashboard, filming the Traffic. The nice thing about this is the added “mirror filter” effect, which makes the video look outstanding.
Here are the 2 videos i found on wimp.com

video 1
video 2

Inspired by those, i created my own video:

Filmed that on the 01/13/2011 at around 6PM (18.00) around Mannheim, Germany, with my Canon Legria HF 200 + my new wideangle lens adapter WD-H37 II. I put my tripod in front of my passenger seat, mounted the Slider on it, and lay one end on the dashboard, this allowed me to move the camera all the way to the front window. Then i added around 4kg of weights to support the rig and reduce shakes from bad roads, I kept the camera in place with some clamps. worked out pretty well for DYI stuff.

– FrooP