it'd suck, but yeah, it would cut down on fuel consumption, that whole aerodynamics thing, and higher rate of fuel flow for the higher RPM you're cruising at, and its not a huge difference per person, but MILLIONS of people doing it across the entire US would save a ton, and i don't see how people say it would up the fuel price? supply and demand dictates that with less demand, price goes down, correct?

less people buying the more they want to sell

on top of that, i'm sure fatal highway accidents would decrease dramatically, and it will also save on wear and tear on your car, over time, less tire wear, etc

the only downside to it would be longer travel times that i see