Each level of Speed (from Terrible to Superb) is defined to be 1.2 times faster than the previous level. A character with Good Speed is thus 1.2 times as fast as a character with Fair Speed. This is not the same progression as for Strength.
Speed Scale increases in the same manner: a Scale 1, Fair Speed individual is 1.2 times faster than a Scale 0, Fair Speed individual. This holds for each increase in Scale:
A Scale 10 Superb Speed animal is 1.2 times faster than a Scale 9 Superb Speed animal, for example.
Speed is not a necessary attribute, of course, and can be ignored entirely if desired. It is included primarily for creatures and vehicles significantly faster than humans.
For comparison purposes, assume a Fair Speed human can run at about 10 mph (16 kph) over some distance, provided they are in shape, of course. Sprinting short distance is somewhat faster. This comes to about 15 yards (meters) per three-second combat round.
Note that in short races, you don’t really have to roll the dice to see if someone of Superb Speed can beat someone of Good Speed he can, and will, much more often than rolling the dice would reveal.
The Speed Scale rises too slowly for comparing such things as race cars or space ships to human movement.
In these cases, either use a rough human Scale, or simply set the average space ship at Space Ship Speed Scale 0, and rate others relative to it. Thus, the average race car will be roughly human Scale 12 or you can simply call it Race Car Scale 0, and compare other race cars to it.
A Space Ship might be Human Scale 100, or Space Ship Scale 0.