Glens, I've gotta disagree with mark on that race car shot. I would have stuck to the rule of thirds on that one. In your shot, it's cool shot of a race car. In my opinion, it could have been a more dynamic photo had the car been to the left and up more...just give you the impression of where that car is headed. Minor details, but in general centerized photos do not excite the eye. I strive to keep the horizon above or below half....always.
love
nick