How to Drive Efficiently On The Freeway

Next time you go dri­ving, stick your hand out of the win­dow and feel how the wind resis­tance varies between 30mph, 40mph, and 50mph.  Air resis­tance trans­forms from being a neg­li­gi­ble force to a very pow­er­ful one after 50mph because that force gets big­ger as the car goes faster.  This drag is neg­li­gi­ble on the street but on high­ways, air resis­tance is a very sig­nif­i­cant force your car is bat­tling against.

More than 60% of the power required to cruise on the high­way is used to over­come air resis­tance.  Main­tain­ing a low speed of 55mph causes your engine to sip fuel rel­a­tive to higher speeds.  You’ll feel how lightly you need to keep the pedal pressed to main­tain 55mph.  The engine also spins at a lower speed (RPM), effec­tively reduc­ing wear, increas­ing longevity and pol­lut­ing the air a tad bit less.

As you can see from this graph, fuel econ­omy only goes one way (DOWN) after 60mph (and most after 50mph).

Dri­ving becomes sooooo easy at 55mph, so much so that I swear it lit­er­ally feels like time slows down. My mind doesn’t get caught up in the hus­tle and bus­tle of get­ting from point A to point B.  Instead it unwinds and dis­en­gages from the process, very much like med­i­ta­tion.  Over­all ride qual­ity is more com­fort­able because the bumps don’t feel as harsh.  Wind noise is less, road noise from the tires is less and the engine is also quieter.

Going 55mph in the slow lane with the cruise con­trol on makes dri­ving very pas­sive.  So pas­sive in fact that my sub­con­scious takes over and I can just dis­con­nect and relax.  There’s some­thing very calm­ing about tak­ing it easy while all the other cars are whizzing past you.  You may feel this sim­i­lar effect when every­body is dri­ving slow when it’s rain­ing and the flow is much more relaxed.

I would even rec­om­mend you try this for the relaxing-effect more than the gas-savings!  It really is that ther­a­peu­tic and errands are less tiring.

You won’t become Neo, but dri­ving slow can make you feel like you’re totally calm, cool and col­lected, able to han­dle any sit­u­a­tion so easily.

This is a very good ques­tion… and the answer is NOT REALLY!  Dri­ving slow doesn’t seem to affect arrival time by more than a cou­ple min­utes because the time it takes to arrive some­where depends on the aver­age speed, not how fast I was try­ing to go on the freeway.

If I am dri­ving 55mph in the slow lane, I can gen­er­ally main­tain that speed on cruise con­trol until I need to exit.  The need to brake is very rare and slower cars do not get in front of me.  I can main­tain an aver­age speed of 55mph effortlessly.

On the other hand, If I am try­ing to main­tain a speed of 75mph, my aver­age speed will be lower than that because I am con­stantly at the mercy of other dri­vers.  Even if I am in the fast lane, I may come upon some­body going slower than me and have to slow down.  I may have to switch lanes to speed up again.  When it comes time to exit, I need to slow down and make my way over to the slow lane.  Often the flow of traf­fic may be too slow to main­tain 75mph.  All of these sce­nar­ios decrease aver­age speed.

For that rea­son alone, even though I am try­ing to drive at 75, my aver­age speed may be closer to 65mph.  That 10mph dif­fer­ence for the free­way por­tion of the trip is not very sig­nif­i­cant, espe­cially for the amount of extra hus­tling that’s being done.  On a 10-mile trip, it will take only 1 minute and 40 sec­onds more to get to your des­ti­na­tion if you’re dri­ving at an aver­age speed of 55 instead of 65.  And this is only tak­ing into account of my time on the free­way. In real­ity, we drive a mix of free­ways and streets.

So let’s say the time has come to exit the free­way and we have to wait at a red light.  Some­times this light may take over a 1 minute to turn green!  Traf­fic sig­nals are the great equal­izer, con­stantly penal­iz­ing (and ridi­cul­ing) those who speed.  Those cou­ple min­utes that are saved by speed­ing may be totally negated by a few badly timed traf­fic lights.  It’s not uncom­mon to see cars that were speed­ing passed me to be stuck at the same light as me.

In a per­fect world, we’d have a non­stop ride to our des­ti­na­tion. But we don’t!

Any­time I fill up my tank com­pletely, I have a habit of reset­ting my odome­ter.  That way I know how many miles I’ve dri­ven on a full tank when it is almost empty.  After I started dri­ving slower on the free­way, my fuel effi­ciency shot up from 300 miles to 360 miles per tank.  That means I went from 25mpg to 30mpg with my 12 gal­lon tank.  In other words, I increased my fuel econ­omy by 20%! That tiny change allowed me to drive 1–3 days longer with­out hav­ing to fill up.  Since then I’ve pushed my effi­ciency prac­tices even fur­ther and have got­ten 420 miles on a tank sev­eral times.