No, 18 mph is not the same speed as 84 mph.
"Mph" stands for miles per hour, which is a unit of speed commonly used in the United States and a few other countries. In this system, speed is measured in terms of the number of miles traveled in one hour.
If a vehicle is traveling at 18 mph, it means that it covers a distance of 18 miles in one hour. On the other hand, if a vehicle is traveling at 84 mph, it covers a distance of 84 miles in one hour.
Therefore, 84 mph is a significantly higher speed than 18 mph.