you cut the car with the right side of the frame... that's like taking a picture of someone's face but cutting off their ear and a slight part of the cheek -- it looks like a mistake.
Were you to try this again, here is what I would do.
1. Setup the car with something much less distracting in the background -- a cityscape if you're near one, a setting sun maybe, whatever.
2. Position yourself a fair distance away from the car, lying on the ground. I'd guess somewhere in the 25' away range, depending on the width of your lens. The lower, the better.
3. Position the camera in "portrait" position, side-camera. Put the car in the bottom of the frame, centered.
4. Have your skater do the trick in front of the car, between the car and you. If you got low enough and he jumps high enough, it will sort of look like he's jumping "over" the car. If you have a wide enough lens, you should be able to get his whole body in frame.
If you can predict with reasonable accuracy how far your friend will be when he does the trick, set your camera to manual focus and set it to that distance. That way he is in focus and the car is slightly out of focus.
Keep the shutter speed around 1/640 if you can, to keep the motion blur to reasonable speeds. Adjust aperture to flavor.