Why do cars average a higher mpg on highways than in the city?

Question

Why do cars average a higher mpg on highways than in the city?

In: Engineering

Answer 1

In the city, there’s a ton of slowing down and speeding up, and you’re never really using any existing momentum to your advantage. On the highway, your car builds up momentum due to the speed, and you usually stay within a ±5mph range, rarely making any sharp turns, and therefore your engine doesn’t need to work as hard to keep you at the same speed.