Many things can go wrong with "Motion blur" shots and I have a high failure rate with them.  This one came out well .  (page)

With "motion blurs" I always try to find something to blur.  Signage is always good -- I wish Laguna Seca had more of it, a lot more.  Concrete walls and bare dirt are terrible: how can you tell if they're blurred or not?  Vegetation is better, as it does blur, but give me a colorful "Edelbrock" sign anytime!