Auto Fuel Saving Tips and Driving Habits

The way you drive will be the single most important factor in saving fuel. You can add all the greatest fuel saving devices in the world and negate the benefit of all of them by driving in a manner that minimizes their savings, leaving you with little or no savings. It’s up to you. It’s like installing all new mini/florescent lighting devices in your home and then leaving the lights on when you leave the room or go away for a week. Would you expect to save on your utility bill if you did that? Of course not, and you can’t expect to save on your automobile fuel bill if you add devices and drive like a race car driver.

Here are some helpful hints that will improve your gas mileage, with a few explanations of the scientific principles behind the hints:

Keep your vehicle clean, inside and out. If you are carrying around a lot of junk inside your vehicle, every time you stop you must accelerate all that extra weight. F=MA, force equals mass times acceleration. The less mass (weight) you carry around, the less force required to get it moving.

A clean, polished, exterior will allow your car to slip through the air with less drag. The cleaner the outside of the car the lower the coefficient of drag and the less fuel you will use. This also applies to other drag inducing items including open windows, extra antennas, roof racks, decorative spoilers, ice, snow and mud. Keep your vehicle as free of extra drag as possible. If you drive a pick up truck, drive it with the tailgate down or install a tarp/cover on the bed. Keep the air filter, oil filter, oil, and fuel filters clean for best efficiency.

One of our tests showed that the addition of 650 pounds of extra weight and a bicycle on a trunk mounted rack decreased the mileage of our Saab 9000 Turbo by 19%. Keep your vehicle warm.

There are numerous fluids in your vehicle that are designed to operate at relatively high temperature. Engine oil, transmission fluid or gear oil, rear end gear oil, and grease on any moving part including your wheel bearings, all create internal drag when they operate at less than optimal temperature. A warm vehicle will produce less drag internally. Also the sooner a vehicle reaches its optimum operating temperature the sooner it will get its best gas mileage. A cold vehicle doesn’t vaporize the fuel to be burned efficiently. If you have a garage, use it, not only to keep your vehicle clean, but warm. Even if the garage is not heated, a warm vehicle parked in it at night will mean a warmer vehicle in the morning. That hot car will heat the garage somewhat. Even if the car is 40 degrees in the morning instead of 20 degrees, that will improve your gas mileage. If you don’t have a garage, cover your vehicle in cold weather with a tarp or blanket. It is surprising how much heat this will keep in the vehicle, plus it will keep the frost, snow, and ice off the vehicle. An engine heater is not a fuel waster if used properly. A core heater, block heater, or other engine warming device will heat up your vehicle cheaper than operating the vehicle will. You can place an electric engine heater on a timer so that it doesn’t waste energy overnight. Most heaters take 30 to 60 minutes to heat up an engine. An added benefit is that you’ll have instant heat when you start your engine. Do not start your engine long before you drive in order to warm the engine. This is a big waste of fuel; you are getting zero miles per gallon while doing this. Only when it is extremely cold (below zero) should you wait more than 30 to 45 seconds before driving. When your engine is extremely cold, start off slower and give the fluids a chance to warm up without straining the engine.

Obviously if a cold car wastes fuel, then combining trips to cut down the number of times you warm up your vehicle will also save fuel. Stopping at the store on the way home from work instead of making an extra trip will probably save enough fuel to drive one mile. Many short trips will give you half the gas mileage as one long trip.

Slow down, both in top speed and in acceleration. The wind resistance of a vehicle increases with the square of the speed. The wind resistance at 70 miles per hour is twice the wind resistance at 50 miles per hour, which is twice the resistance at 35 miles per hour.

On short trips and between stops the rate at which you accelerate is even more important than your top speed. Acceleration from zero to 60 miles per hour in 10 seconds will use more fuel than acceleration from zero to 60 miles per hour in twenty seconds, and coverless ground in doing so. A slow constant acceleration will save you lots of fuel.

Coast, once you have built up your kinetic energy (KE=1/2MV2 Kinetic energy equal one half mass times velocity squared) use it to transport your vehicle. Every time you use your brakes you throw away your kinetic energy. Rather than cramming on the brakes to stop, plan ahead and coast with your foot completely or partially off the accelerator petal as you approach a stop or a turn. Do not decelerate by using the engine to slow you down. This is as bad as using the brakes. When going down a hill either coast or keep the throttle setting high enough to keep the engine from slowing you down, unless of course the hill is so steep you need to slow down. When coasting at idle throttle, do so with the clutch disengaged, but still in gear for safety. The smoother the deceleration the better the gas mileage. If you really want to do this exercise with some purpose, put a full cup of hot coffee on your dashboard just above your lap, and decelerate without spilling it. I’m just kidding, this would be dangerous.

Look ahead. There are many things you will learn while practicing high mileage driving. A lot of these I learned at the tutelage of my dad while he taught me how to drive in a three cylinder, two stroke Saab. It only had about 25 horsepower and we lived in the foothills of the Green Mountains of Vermont. The lessons I learned in getting up and down hills apply perfectly to high mileage driving. Look ahead sums them all up. When you see an uphill coming up ahead, don’t wait until you get to the bottom of that hill to push on the accelerator. If you do, you will need eccess accelerator to get up the hill. This affects your gas mileage. What you want to do, and what I had to do with the Saab is to gradually accelerate before the hill and carry some extra speed into the hill so that the Kinetic energy can be used to get you up the hill. As you get near the top of the hill you can back off the accelerator and “coast” over the top of the hill with somewhat less than normal speed. Why would I want to slow down at the top of a hill? Because I have free Potential energy at the top of the hill that I can use to accelerate my vehicle down the other side of the hill without using up fuel to do so. PE=mgh Potential energy equals mass times the acceleration of gravity times the height of the vehicle from the bottom of the hill. When I get to the bottom of the hill this potential energy will have been converted to Kinetic energy that before I had to build up by burning gas. If I had crested the hill with my normal speed, I would have had to use my brakes going down the hill or build up excessive speed. Even this excessive speed is not efficiently used by coasting because while I am carrying the excessive speed the wind resistance is stealing it away from me faster than I can convert it to distance traveled. When approaching a curve you want to slow down, again without using the brakes, coast up to the curve and gradually accelerate after the curve, or carry the extra spped you may have entering a curve by sacrificing comfort and enduring the lateral acceleration. Be sure your speed is not unsafe though. If you have to use the brakes for safety, that is more important than high mileage.

When approaching a traffic light or line of traffic, adjust your speed so that you won’t have to stop. Slow down gradually and time your traffic lights and congestion so that you get there with a clear road and as much speed as you could conserve during your approach. I won’t discuss stop signs much because efficient driving is contrary to stop sign protocol. I will say that approaching a stop sign should be done with natural deceleration and as little brakes as possible.

Shift early. If you have an automatic transmission you have probably noticed that if you want the transmission to shift early you can help it along by momentarily coming off the accelerator at the proper speed for each shift. Knowing the right time is part of knowing your vehicle. If you have a tachometer you can encourage the transmission to shift when you have 2000-2500 RPM. If you don’t have a tach, you can get used to the sound of your motor to apply this technique. For a manual transmission you would like to shift when you get to 2000-2500 RPM which will put you in the next higher gear at around 1500-2000 RPM. Actually I shift at 1500 RPM and into the next gear at 1000RPM, for best mileage. Without a tach just shift so that your engine is not revving too much and so that in the next higher gear you still have enough torque to prevent your engine from bucking and hesitating. When lugging the engine on a hill you may need to shift your automatic transmission into a lower gear manually to keep your engine running smoothly. Just try to keep the transmission in a high gear.

You will notice when you shift that the vacuum goes down when you shift to a higher gear. This is not a reason to stay in a lower gear to keep the vacuum high. This would only use more fuel because in the lower gear the engine is turning faster and sucking in gas on each revolution. At the higher gear selection you are at a lower vacuum but the lower RPM more than makes up for it.

When stopped for a traffic light put the automatic transmission in park. This lets the engine idle with the least resistance. If it’s going to be a long light shut off the engine. While you’re sitting there you’re getting zero miles per gallon. Never use the accelerator to hold your vehicle on a hill with an automatic transmission or with a manual transmission.

Keep it working. Vehicle maintenance is important to efficiency and long life. I used to buy vehicles that other people had already abused. Now I only buy those that I know the history of. If not new, I want to know how it was taken care of. Most important are oil changes. I insist on an oil and filter change every 3000 miles (5000 km) unless you use recommended synthetic oil. I haven’t really researched the gas mileage performance of different brands of oil. I have heard that there is a difference but I don’t know if it’s worth using an expensive oil unless it is a synthetic oil. I prefer to treat my engine every 25,000 miles with a true engine treatment. I was sold on Teflon back when Slick-50, and you had to get it from a traveling salesman. I had a twin engine ultralight aircraft on which I treated only one engine. By the time I figured out the difference, I had lost the treatment for the other engine. To match the RPMs of the engines during flight I would have the throttle of the treated engine back about 1/4 of the way. Also when it was time to rebuild the engines the treated one lasted about six-month longer on a four-year life.

If your vehicle has a choke, make sure it is not sticking. A way to tell if it is sticking is black smoke in the exhaust, especially after five minutes of driving. Do not rev your engine when it is cold. This will wear the engine parts quickly. Do not idle your engine for long periods of time. It will carbon up your cylinder heads and wear down your cylinders because the rich idle mixture washes off the oil on the cylinder.

Don’t rev your engine before shut down. In fact don’t rev your engine period. It puts stress on the engine that is designed to have a load on it when running at high RPM. Also the gas thrown in when revving will wash down the cylinders and lose the lubrication of the oil. Revving also causes gas to blow by the rings and contaminate your oil.

If your vehicle isn’t fully electronic, make sure you tune it often enough to ensure proper operation. A tune up is cheaper than the wasted fuel and worn engine. If your vehicle has a carburetor there are many fuel saving tips and modifications available from Eagle Research. They are on the Internet.

Tires are a big factor to high mileage. I keep my tires pumped up to manufacturer’s recommendations. I do this for two reasons. One, I have a couple of mag wheels that are porous and gradually leak air through the rims, and two, higher pressure means lower rolling friction from the tires. Wide tread tires look good but rob mileage, follow manufacturer’s recommendations.

Radial tires are much better on gas than bias ply tires. Wheel alignment is critical. If your tires are wearing out in a certain pattern then you are wasting tires and gas. The energy it took to scuff those tires to cause the wear came from your fuel tank. Be sure you get four-wheel alignment. Use the same size tire all around. In the summe,r use summer tires all around.

Using power accessories will lower your gas mileage, especially air conditioning. Driving with your windows down is not much better. A good compromise is to circulate cool outside air through your heater/ventilation system.

Be gas wise. Gasoline is sold by the gallon, not by the pound. Get your gas when it is the most dense. When it is cold, it is most dense. Early morning is the best time to get the most gas for the buck.

Do not buy high-octane fuel unless it is require to keep your engine from spark knocking (pinging). Higher-octane fuels contain larger hydrocarbon molecules, which take longer to burn. This will mean that some will burn in the exhaust pipe or catalytic converter instead of in your engine. Avoid filling the gas tank to the top. Gas is stored underground where it is cooler in the summer. If you fill up, the gas will expand when it warms up and some may overflow. Make sure your gas cap seals well and no fuel is ever leaking onto the ground, especially when sloshing around corners.

Choose your road. If you have a choice of routes, choose the one with the smoothest road, the least hills, the least turns, the least traffic, and the least head wind. This may mean choosing a forested back road with no traffic rather than the open highway with lots of traffic and rough surfaces. Hey, you might find out that the drive home away from the rat race even helps you relax.

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