Increase Gas Mileage by Using Your Tachometer

What is that extra dial on the dash that looks like a speedometer? That's a question some of us may be asking. That dial is called a tachometer and it measures how fast your engine is running. People who have cars with a manual transmission can use it to indicate when to shift. But, did you know it is also the best gas saving device on your car?

I drive an E350 Ford Super-duty 12 passenger van set up for towing a 32' travel trailer. Ninety-five percent of the time it is not towing but carrying me around town. The gas mileage on this beast is lousy. I utilize every trick in the book to achieve optimum mileage and my tachometer is most important after the speedometer. When using the tachometer I estimate my gain is an extra two to three miles per gallon even while towing. Don't believe me? Edmunds tests conclude that moderate over aggressive driving will result in a 37% increase in gas mileage.

First thing is to know is what the numbers on the dial represent. Each number represents thousands of revolutions per minute, (RPM) which your engine is turning. It makes sense, the lower the RPM the slower your engine is turning and you use less gas.

In photo #1, you see my tachometer at idle. The gauge is a little past 500 RPM, and the speedometer is at zero. The needle is also steady, if it jiggles I know the engine is running rough and needs to be serviced. One more thing you might notice is that the temperature gauge is at C or cold. When the engine is warm, the tachometer will register under 500RPM. If it does not, once again I know the engine needs attention.

In picture # 2, I am accelerating on an entrance ramp to the expressway. My tachometer reads just over 1000 RPM and my speed is about 35 miles per hour (MPH.) To achieve this speed without greatly increasing my RPM I had to gently accelerate instead of pushing down hard on the accelerator. I am still keeping up with the traffic flow but my engine is running efficiently.

In Photo #3 I am cruising down the highway at the posted speed limit, 55 MPH. My tachometer reads just over 1500RPM. So it takes just an extra 1000RPM over idle to drive at this speed. Now I set my cruise control and the engine will stay at a steady 1500RPM. The highest RPM my engine reached while merging was just under 2000RPM.

When towing I add about 1000RPM to each step, even cruising. Once you are accustomed to using your tachometer, you will notice differences when you have passengers, or heavy loads in your vehicle. While driving I glance at my speedometer and tachometer at the same time and adjust my speed or RPM as needed. Often I can sightly lift my foot and reduce the RPM without affecting my speed. You will soon become accustomed to doing the same and be on your way to big savings when you drive.