With this shot I wanted to test the depth of field a telephoto would deliver. I wanted the car and driver in focus, the background into bokeh. Since the car is in this photo the long way, you have to make sure your depth of field covers more than the driver's eyes. In this case I went wanted from bumper to bumper.
I accomplished this by going f5.6 on an APS-C Pentax K-5 at 220mm (330mm equivalent 35mm). I think it worked pretty well, let me know what you think!