Since the 'speed' in the KE formula is squared, if the car's speed increases by 5 times, its kinetic energy increases by (5²) = 25 times.
The loss of kinetic energy in a skid is just the wo0rk done by friction between the tires and pavement. So the skid distance is proportional to the initial kinetic energy, and the car must skid 25 times as far when it enters the skid at the higher speed.
