system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: why does faster highway driving use less gas per mile than driving slower in the city?
gpt
It takes more gasoline upfront to accelerate, especially from a stopped position, than it does to maintain speed on a highway, especially since you've got some sort of momentum help carry your car. Also, idling at a stop = burning gas without covering any territory. So you're reducing your average miles per gallon towards *zero* very frequently when driving in a city because of all the stopping and going and idling. On a highway, you're just... going. Smooth sailing, so you're covering more territory per gallon burned.