Why does lowering the speed limit on the highway lower your fuel consumption?

Question

Why does lowering the speed limit on the highway lower your fuel consumption?

In: 3

Answer 1

It doesn’t always. If you lower from 80 to 60, you eliminate a large amount of aerodynamic drag, and thus fuel consumption, for probably all cars. But if you go from say 60-50, you might increase fuel consumption since cars may not be operating at their most efficient speed, which is usually somewhere between 50-60. This number has been creeping up over the years as cars have become much more aerodynamic.