 My Experiment In Fuel Economy: Getting The Most From Your Gas
"Kilometers are shorter than miles. Save gas, take your next trip in kilometers."~George Carlin
With all the talk of about the effect on the economy, environmental problems, and politics that oil has, I have decided to do my part to conserve its use. The problem is, when I go on the Internet, ask at the dealership, or even inquire at Autozone, I get mixed messages about what is, and what isn't, good for my car. I decided to do some real world research to see what really helps my fuel consumption.
I drive a 1999 Mercury Sable with a 3.0 Liter V-6 with a 4 speed automatic transmission. The manual claims 20 mpg in the city and 28 mpg on the Highway. It also says I have an 18 gallon fuel tank. It is also important to note that the "low fuel light" is set to go off when the fuel tank is down to 1/16th of a tank (1.125 gallons). Since I do not want to infringe on that reserve, I will round my estimations to be for a 16 gallon gas tank, since I will go by when the "low fuel light" goes on.
Before I start my experiment, I wanted to get more information on how automakers determine fuel economy. It took time and patients to discover the facts about this. As they say, "the devil is in the details.
It turns out, Miles Per Gallon (MPG) is determined under laboratory conditions. These conditions are the most unrealistic conceived. Highway miles are determined by testing the car on rollers (simulating a flat surface) going along at 55 Miles Per Hour (MPH), on a flat level road. No wind resistance, no changing lanes, no accelerating.
City mileage determination is even more precarious. On rollers, cruising at a speed of 30 MPH, they stop every 5 miles, to simulate stop and go conditions. On a good day, it seems I keep hitting stop lights every half mile or so. Not to mention the fact the I am swerving in and out of traffic.
It appears that MPG ratings are more fiction than fact when it comes to fuel economy standards. I believe that if the Federal Government wants to regulate fuel economy, they need to require the auto industry to use more realistic simulations. The concept of "ideal conditions" only works if relived in an "ideal world."
Back to the experiment. To begin with, I filled my tank at the local Walmart with Regular Unleaded Gasoline, and drove normally. To fill my tank at the moment my light went on cost me $29.00 at $1.98/ Gallon. That filled with it 15 gallons of fuel. I set my mileage counter to zero, then, drove as I normally would. In an out of traffic, accelerating at stop lights, not limiting my speed or my RPM's.
When it was all said and done, the light cam on at 373 miles. That works out to an average 24 miles per gallon. That is mostly in city. I was rather surprised at the efficiency of my vehicle. It is an older Mercury Sable.
The next step was to fill the vehicle up as normal and control the RPM's. Believe me, this is easier said than done. I have decided to never allow the vehicle to accelerate higher than 2100 RPM's. It takes steady control of your pedal, but it can be done. Instead of trying to be the first past the red light, I allowed myself to enjoy the day. Feeling the wind in my face, and the sun on my skin. Instead of leaving for an appointment at the last minute, I decided to leave a little earlier and spend some extra time on the road, enjoying the radio. I accelerated gradually, anticipated stopping and coasted to minimize braking, and minimized air conditioning usage.
Surprisingly, the "Need Fuel Soon" light did not turn on until I had surpassed 402 miles. I was shocked. By just changing my driving habits, I had gone from 24 to 26 MPG. It may not sound like much, but imagine if you had to walk those extra 2 miles to get a bottle of milk, or more gas for your car. Suddenly 2 miles can mean a lot.
The next phase of my experiment was to put premium gas in the car. I was not really confident that there would be a notable improvement on performance, but for the sake of the experiment, I am willing.
I filled her up at the local Walmart, paying $2.12 per gallon, reset the trip odometer, and convinced myself to keep the RPM gauge under 2100 ,still. From the beginning, the acceleration seemed smoother. The engine did not make quite as much noise. It felt a little more powerful for some reason. I do not know if this was true or perceived performance gain base on a Pavlovian response.
To make a long story short, I was watching the odometer toward the end. It past 373 miles no problem. Then, coming upon the 402 mile mark, I was expecting the light to turn on. It did not. In fact, the light did not go off until I was approaching 414 miles. Just by changing the gas, and my driving habits I increased my mileage to 28 MPG. I had decreased the fuel consumption by 10%.
I must admit that my little experiment was not "scientific" in the strictest sense. Some of the days I drove were rainy, traffic conditions varied. The one thing that this shows, as much in our driving habits, as well as in life, that a change in focus on what is important to us can effect the world in a definite positive way.
Here are twelve more tips to improve fuel economy in your automobile:
1. Keep your engine tuned up. Incorrect fuel ratio, bad spark plugs and incorrect spark timing can have a big effect on gas mileage.
2. Don't use your air conditioner (A/C) unless you really need it. The A/C compressor puts an extra strain on the engine.
3. Make sure your tires are properly inflated. Under inflated tires cause more resistance to travel.
4. Avoid stop and go traffic by taking alternative routes or less congested travel times.
5. Ask other people with the same type of car what kind of gas mileage they get, it may alert you to a problem with your car.
6. Use a good engine oil, preferably a synthetic or standard oil treated with a friction reducing oil additive. These have been known to improve fuel economy by as much as 12%.
7. Reduce the weight in your vehicle as much as possible.
8. Use your cruise control whenever on straightway roads with minimal curves. Using cruise control on curvy roads reduces fuel efficiency overall. Cruise control computers were designed for the best fuel economy in a straight line.
9. Keeping your highway speed at 65 mph can improve you gas mileage by as much as 25%, compared to 75 mph.
10. Avoid trying to increase speed while climbing a hill, your engine is already working hard trying to overcome gravity.
11. Keep your windows closed when possible. Open windows actually produces drag and reduces gas mileage at highway speeds, compared to using the A/C.
12. Remove accessories, such as luggage rack, etc. that lower the aerodynamics of your vehicle.
"You must take personal responsibility. You cannot change the circumstances, the seasons, or the wind, but you can change yourself. That is something you have charge of."~Jim Rohn
The next article in this series will be on engine modifications to improve gas mileage, where I interview Chad, an avid car enthusiast.
Last edited by DanielSlack : 05-29-2009 at 12:05 AM.
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