I did read a little bit about the work Mercedes did( Bionic) and the boxfish. That would seem to be close to the optimum shape for a car.
The Bionic Car project - Image 12 of 12
This would make it seem that it is better to 'bend' the air(image #2) than to cut through it for a passenger vehicle. Formula One or Indy car designers feel it's better to cut through the air, evidenced by the pointy fronts and rounded sides. I was thinking that, for a motorcycle( being relatively tall, short, and narrow) a modified wedge-low pointy front, wide@ the beltline and tapering top and bottom(all sharp angles)- would be best. Now I have no clue!!!