When it comes to saving money on gas and improving mpg, it doesn't pay to get where you're going faster. While every car is a little different, the general truth is that fuel economy nosedives when you cross the 55 to 60 mph threshold.
Check out the graph on this page from fueleconomy.gov. It looks like an eastern Kansas hill — there's a sharp rise, a brief plateau, then a sad decline. The sweet-spot for fuel economy falls between about 40 and 60 mph. For every 5 mph over 60 you drive, the site says, you're basically paying an additional 20 cents more per gallon for gas.
But in today's fast-paced America, slowing down can be tough. Even though driving faster (say 75 instead of 65; 55 instead of 45) rarely saves an appreciable amount of time, it's hard to break the gotta-get-there habit. Plus, few people enjoy the glares and obscenities that often come from those annoyed because you're going 5 mph under the speed limit instead of 10 mph over. Nevertheless, you'll get a good rise in mpg if you consistently lock your cruise control on the speed limit, or even just a little under, for high-speed driving. Just take the slow lane (think of it as the scenic lane) and remind yourself how much gas and money you're saving as the rat race flies by.
As you might guess, changing our national speed limits would be a game-changer for saving oil. We've been down that road before: the change to 55 mph was a key factor in reducing our oil consumption in the 1970s. Should we do that again? Post a comment below to share your thoughts.
John Rockhold is a green car enthusiast and Contributing Editor for MOTHER EARTH NEWS. Find him on Google+.