There is no scientific evidence that a horse's color determines how fast it can run. A black horse isn't inherently faster than a chestnut, and a spotted coat doesn't confer any racing advantage.
What Actually Influences Horse Speed
Breed: Thoroughbreds and Quarter Horses are renowned for their speed.
Genetics: Inherited traits such as muscle composition, cardiovascular efficiency, and stride length play a major role.
Training and Conditioning: Proper preparation is essential for unlocking a horse's speed potential.
Diet and Nutrition: A balanced diet supplies the energy and nutrients required for peak performance.
In short, a horse's color has absolutely no bearing on its speed.