For this blog, I'm only going to be looking at examples of speed displayed in Fast and Furry-ous, the first short in which the Road Runner appeared.
The above scene is the clearest example we get of the Road Runner's speed. During this chase, the Road Runner takes just 0.76 seconds to run a complete loop around one of the roads. So all we need to know now is how long those loops are.
They appear to be running on a single lane road, which tells gives us a width to work off of, as US interstates have a standard road width of 3.7 meters.
Measuring this out, the Road Runner is running a loop around a circle with a 45 meter diameter, or a 22.5 meter radius. The circumference of this circle would be around 140 meters, and since the Road Runner is lapping this in 0.76 seconds then...
v = d/t
- d = 140 meters
- t = 0.76 seconds
140/0.76 = 180 m/s
Now it's time for another question, how fast isn't the Road Runner?
Conveniently, this episode gives us an answer. Wile E. Coyote straps on a pair of jet boots that, as seen, make him marginally faster than the Road Runner is. All we have to do is measure his speed with said boots to place a rough limit on the Road Runner's abilities.
According to the Space Jam manual, Wile E. Coyote is 1.17 meters tall, so that's what we used for our measuring stick here. Simply tracking Wile E.'s motion after he begins moving shows that he descends the hill at a rate of 305 m/s.
- How Fast is Road Runner? (Lap Speed) - 180 m/s ~ Mach 0.5, Subsonic Class+
- How Fast is Road Runner? (Jet Boot Speed) - 305 m/s ~ Mach 0.9, Subsonic Class+