* Average speed doesn't tell us the final speed. Average speed is calculated by considering the total distance traveled and the total time taken. It doesn't tell us how fast the car was going at any specific point in its journey.

* Starting from rest means the initial speed was 0 mph.

To determine the final speed, we need more information:

* Was the car traveling at a constant speed? If so, then the final speed would also be 80 mph.

* Did the car accelerate or decelerate? If the car sped up, the final speed would be greater than 80 mph. If the car slowed down, the final speed would be less than 80 mph.

Let me know if you can provide more details about the car's motion, and I can help you calculate the final speed!