You should read the first couple of chapters in Mr. Tompkins in Paperback by George Gamow. In his dreamland called Wonderland, the speed of light is about 10 mph and Planck's constant is 1. Not only does he observe relativistic effects, but quantum mechanics as well. There is even a chapter called quantum billiards. It explains why my break speed never goes above 10 mph and why there is so much uncertainty where my CB is going.