Gas Mileage

Interested in helping the environment and spurred by gas prices, I recently decided to enact a science experiment. This details my experiment.

Results (short version):
Driving 65 mph does save gas!
Ranger - Previously 19 or 20 Miles per Gallon (MPG)
Now 21 or 22 MPG
Escape - Previously 18 or 19 MPG
Now 20 or 21 MPG

History:
In the 1970's the was a gas shortage. To help reduce the need for gasoline, a national 55 Miles Per Hour speed limit was created. The reasoning was simple: After 55 Miles per Hour (MPH) the fuel efficiency of any vehicle will decrease exponentially. Eventually, gas was again in ready supply and people "can't drive 55". So, slowly those limits were lifted. Now, speed limits commonly reach up to 70 MPH in some stretches. And while cars are now more efficient than ever, science hasn't cured the 55 MPH drop off. I was reminded of this recently when I read a story saying that you could increase your gas mileage if you'd just drop down to 65 MPH. So, I decided to give it a try.

Hypothesis:
If I drive no more than 65 MPH, it will increase my gas mileage. And not just a bit, but a noticeable (and therefore WORTH WHILE) difference.

Vehicles involved:
1999 Ford Ranger, 2WD, Extended Cab, 3.0L V-6 engine with 5-speed manual transmission
Approximately 135,000 miles
Before experiment I would get around 19-20 MPG
EPA Rates this vehicle at 19 MPG city / 24 MPG freeway / 21 MPG combined

This vehicle is mainly driven to work and back. Bumper to bumper traffic from Oak Cliff up 35 or Zang/Beckley to the Dallas North Toll Road. There traffic generally opens up and I can drive 65 MPH to 635. That is where I work. The drive home is generally slower.

2004 Ford Escape, 2WD, 3.0L V-6 engine, 4-speed auto with Overdrive
Approximately 45,000 miles
Before experiment we would get around 18-19 MPG
EPA Rates this vehicle at 17 MPG city / 23 MPG freeway / 19 MPG combined

This vehicle goes the same route as the Ranger, except it stops at the Toll Road and Lovers Lane. It is also the weekend driver for our family.

Experiment:
The experiment is simple: Drive no more than 65 MPH. The first tank of gas I really struggled remembering to keep the speed down. So, I took a sticky note and put it on my speedometer. It's much easier to remember to drive less than 65 MPH when you can't see the speedometer at 70+ MPH. Previously, I would regularly drive up to 75 MPH when traffic allowed.

Results:
The results are immediately seen. From one tank to the next, I saw a jump in roughly 3 MPG, despite I drive mostly in stop and go traffic. In the Escape, the change has been comparable. The greatest was this past weekend in the Escape. We took a trip approximately 180 miles one way, mostly freeway. On that drive we averaged as much as 23 MPG!

Recommendation:
Once again, environmentally friendly and cost efficiency work in perfect harmony. Dropping your max speed just a bit to 65 MPH will save you mileage! Considering the continued rise in gas prices, can we afford not to? And, of course, saving gas mileage means saving pollution. It's a win-win.

I encourage everyone to try this earnestly for just a single tank of gas. Put your sticky note on the dash and stay under 65 MPH. You will see the difference at the pump, too!

Just fill up your tank and reset your trip meter. After driving a tank at 65 MPG, fill it up again. Divide your mileage against how many gallons you put in the tank. That will give you the Miles per Gallon.