The correct statement is: "The vehicles have the same speed, but different velocity."
Explanation: Speed is a scalar quantity that refers to how fast an object is moving, and both the motorcycle and the car are traveling at 40 miles per hour, so they have the same speed. Velocity, however, is a vector quantity that includes both speed and direction. Since the motorcycle is going north and the car is going south, they have different velocities despite having the same speed.