[tcgv]

If my car is travelling at 60 mph and there is a car in the opposite direction also travelling at 60 mph (according to a inertial frame of reference) then classical mechanics allows me to say that from my point of view the other car is indeed traveling at 120 mph. But special relativity only allows me to say that the other car is travelling at 119.9999999999990394 mph from my point of view. The higher the speed, the greater the difference in the results from "classical mechanics" and "special relativity" will be.