The subject of lowering fuel consumption has aroused in this board, as it did in others. In general it is a growing tendency in the western world, mainly in Europe, to consider gas consumption and air pollution as a growing factor in car design, marketing and in driving styles. Adopting the right driving style can help reduce gas consumption by tens of percents, even by 40% and more. This is a hugh save, which can be made ever so great when applied in over a greater population of driving, even be it a small precent of the drivers in the respective state.
Reduction of gas consumption should not be viewed as less spilt gas per se. The same driving style will reduce pollution, increase the life-spawn of the motor-oil and reduce the wear on the whole drivetrain and the tires, making the expenses ever so smaller. But, beyond all subjects of reduced wear, pollution and consumption of petrol, driving more economically always means driving more safely.
Research show that as gas prices increase, the amount of collisions is reduced at a constant rate. The same result can be achieved in a reverse manner if we try to make our driving style more economic, and that's what really matters.
The concept
Less fuel being injected into the engine equals a better fuel consumption and lesser friction within it, and thus less heat. This reduction of friction and heat will reduce the toll on the motor-oil, which will maintain it's original quantity and natural qualities for longer. Less fuel injection also means a lesser pollution of the air through the gases projected out of the exhaust. In theory, petrol engines should not pollute the air at all. The only exhaust gases should be water vapor and co2. However, no modern petrol engine has reached the ability to exploit 100% of the petrol injected through it, so some of it is being projected as drops of unburned fuel, or semi-burt fuel (carbon monoxide) and other gases.
Working the engine at a reasonable rate of RPM and with a reduced flow of petrol, allows it to make better use of the given amount of petrol. The reduction of friction within the engine and the better durability of the oil would prevent the generation of spongy residues within the engine, which will in turn contribute to a further reduction of pollution.
So the solution is simple: Pressing on the throttle more gently and more briefly reduces the amount of fuel that flows into the engine, and gives better mileage. The more gentle acceleration also does wonders with the grip of the car and it's stability, with the wear of the tires, and with your ability to interact with traffic around you. Simple.
Car Maintainence
Proper maintenance of the car is the first step in achieving a lesser consumption of petrol, and here we again run into tires. The first step starts which purchasing them. There are some "eco" or "energy" saving tires meant to give a longer mileage and a lesser rolling resistance (followed by a reduced fuel consumption), but many of these tires (though not all of them) have poor grip levels, which might be enough to scare you off.
A tire with a soft rubber compound (a lower treadwear rating, between 400 to 300) gives more grip on the expense of a greater rolling resistance and also more pronounced effects of wear and aging. However, these effects are canceled by the tires' good grip and safety, as well as a reduced wear on the other mechanical parts involved. Choose a four, identical, good and new tires. The tires should obviously fit the job. People who go cheap and keep the winter tires on in the dry do more harm than good.
The tires should be replaced once every 70,000km or three years, which ever of the two comes earlier. In countries with cooler and more dry weather, the tires' aging process is slowed down to a point where it can be used for four years instead of three. In any case, getting into the habit of parking the car regularly in the shade can help the tires maintain their qualities more effectivelly.
The front pair of tires should be switched with the rear pair about every 15,000km, and while you're at it, you can have the wheel alignment checked too. You need to check the tire's pressure once every two weeks and before any long or demanding drive. In any case of doubt, choose to over-inflate the tires rather than under-inflating them. If your tires have some inherent problems (unusual wear patterns, noises or rolling resistance) you can balance it out by choosing to drive regularly with the tires inflated by 1 to 3 psig over the recommendations of the manufacturer.
Ensure proper inflation with a personal guage. A pencil gauge is likely to be more accurate than the one at the gas station, and will be resistant blows. If you don't have it on you, you can make sure the pump doesn't hoax you, by applying it two or even three times on each tire. It's also recommended to deflate and re-inflate the tires periodically (every six months, as a rule of thumb), to get rid of the some of the moist and chemical residue inside the tire. A personal compressor can provide you with a more clean and dry air for this purpose.
The dampers should also be maintained. Economy-style driving, lower speeds and driving on quality roads can increase their mileage to over 100,000km, but they usually need to be replaced at around 70,000km. The car might start to feel "rocky" but not necessarily.
The drivetrain should of course be maintained too. Make all the required periodic treatments, and use synthetic motor-oil (if the manufacturer allows). Note that the recommended period for replacing the oil, as it appears in the manufacturer's sheet, is based on cruising down a highway and not on driving that involves constant changes of speed. Additionally, manufacturers market their models as being reliable, and post longer and longer periods for oil replacement.
Replace it earlier, especially in cars with an automatic transmission (once every year or 50,000km) Replace it earlier for cars with a large mileage (over 200k annually). The lubricants and antifreeze should also be checked weekly for the right level and for changes in texture. The oil filter should also be checked and replaced periodically (every two years). New engines and engines after certain mends or replaced oil should be driven more subtly for a certain amount of miles, preferably about 5000km.
Driving Logistics
The next big way to save fuel starts with the logistics of driving: Estimate the arrival time, set out five minutes "too early" and be sure to note the people at work/home/whatever that you will be late, in cases of bad weather or heavy traffic. Just making allowances for being late reduces stress and increases economy and safety, where the actual loses of time are usually much less large than they seem.
Another solution is not to drive. This is relevant for short drives of up to fifteen minutes, which can be replaced by walking. These solutions also yield health benefits of reduced stress and increased fitness.
Driving Style
Stay in the right gear. In a manual transmission, stay in the gear that gives you a steady rate of 2500 to 3800 RPM (as a rule of thumb, it varies from engine to engine). Too low or too high revs will increase gas consumption and increase wear. With that being said, most manufacturers recommend that every certain period (sometimes on a weekly basis), the car should be driven for several minutes in higher revs so that it can be better lubricated and cleaned out of sooth. This should only be done in drives where the engine has already reached working temperature (around 96 degrees celsius).
The automatic transmissions are best kept in D. Neutral should never be used, other than long stops, where it is usually best to stop the engine altogether (when stopping for over two minutes, as a rule of thumb) and the gears are to be used in cases such as driving on a long downhill slope. In a manual transmission, don't go down through the gears as you brake. Just brake, let the revs drop and when they start getting too low, declutch and re-engage the desired gear once you finished braking.
At a standstill, a manual transmission is best kept in neutral. However, remain in first gear for as long as a car has not come to a halt behind you, so you can accelerate forward should you be threatened from behind. Constantly pressing the clutch or even just having the foot hovering over it during a standstill will wear out it's pressure plates.
When you start a car with a manual transmission, press the footbrake, release the handbrake, declutch and start the engine. This can reduce the wear on the starter very significantly. After turning a car on, stay in neutral (or park, in an automatic) for about twenty seconds until the RPM evens out. Start driving very gently, without operating anything electric (like air conditioning or lights) for the first minute or so, and drive gently in general for the first ten minutes of the drive (longer in cold weather). After lighting up the car's headlights (which should be used in every drive), turn them off should you be caught in heavy traffic jams (where you need to apply the methods mentioned in my former article to save a lot of extra fuel and increase safety).
In all transmissions, make light hand motions, without gripping the knob like a fighter jet stick, but rather but your palm on it and move it to the desired location. The ability to heel and toe when downshifting in a manual transmission is much appreciated here, although not crucial in modern transmissions. Don't leave the hand on the gear lever, as it will put pressure against the linkages and reduce your steering control.
Press the pedals gently. Pressing the gas gently and lightly has an obvious contribution to a lesser consumption of gasoline, but in fact pressing the brakes more lightly also helps just as much. By braking relatively hard, we stop over a shorter distance, which means we kept the throttle open for an extra few tens or hundreds of feet. Instead, we can ease off of the gas pedal (gently) far more early, pause for a little, and than brake lightly over a longer distance.
With that being said, pressing the brakes too lightly and over a very long distance is going to put more wear on the brakes. Don't brake too early, and when braking from a high speed to a significantly lower speed, you need to make a few shorts "pauses" in the braking process where you ease off of the brakes for a moment or two. This can reduce the wear very significantly. Trucks can use their retarders, exhaust brakes and other braking measures too, when driving in the dry. Of course slowing down like this requires looking further ahead and anticipating slow-down from a much larger distance, which is a ground rule of safe driving in general.
Maintaining the proper following distances is also helpful in reducing the gas consumption. Some drivers thought on the option of sticking closely behind big rigs as to sucked into the vacuum behind them, thereby reducing gas consumption. Clearly this is not safe, but in fact it also doesn't really increase the economy. By not maintaining the proper following distance you force yourself to brake quite mildly for every time the driver ahead slows down, even very slightly, which more than overweighs the benefit of the so-called "slipstreaming."
Driving the appropriate speed also helps. As a rule of thumbs, engines and tires feel more comfortable at speeds that don't exceed 100km/h. If the limit is higher, drive at that pace in the right lane until the engine gets the right temperature. Highway driving can also be used as an opportunity to purge the engine. You put the transmission into a low gear for low RPM (2-3k of revs) and drive like that for two hours, once every year or so. This kind of drive helps to dispose of soot in the engine.
Using the air conditioning is a craft by itself. There is no need to use too highly of a ventilation. It is usually noise, energy consuming and not too efficient. Don't use the A/C in the first few minutes of driving. If it's summer and the standing car is hot, open up the doors (and the sunroof, if available). Just opening them for two minutes alone, will cool down the car significantly (and this I say from my experience under the Israeli sun!).
Of course you need to remember my advice of trying to park the car in the shade regularly. If possible park with one window opened to a slight crack, and cover the windows and windscreen with special "screens." Even a small "net" that fits onto one of the windows can keep the car much cooler. Keeping the wheel covered with a towel is also important.
In nice weather, you can open the front windows for ventilation. The open windows also give you an addition audio input of the road around you, and a feel of the car's speed through the air flow. In high speed driving (over 60km/h, as a rule of thumb), choose to drive with closed windows (other than a small crack at a top of one of the front windows, for ventilation in both the winter and summer.
Start the air conditioning with "fresh air", so that unwanted ornaments and particles of rubber be filtered out. Near the end of the drive, again stop the air circulation for fresh air, and stop the cold air flow, just leave the vent pumping air at the highest rate. At this position, the air conditioning unit is designed to dissolve itself of unwanted scents and residues through a special tube. Periodically activate the cold A/C in the winter, and the heating in the summer, so the mechanisms (and especially their rubber bands and oils) are not worn out.
In a hot summer, take one time to put the car under the sun, open the hood, start the car, with the hood and all doors and windows fully opened. After five minutes, apply the vent to full power. After another five minutes, apply the heating to maximum power too. After another five minutes shut it down and let the open car to "roast' under the sun for an extra twenty minutes. This helps clear out the air inside the car like a wonder.
Speaking about windows: Always leave one of the front windows slightly open. In the winter, it helps to stream in cold and fresh air and prevent fatigue, and in the summer it helps to renew the oxygen inside the car. Don't drive the car with windows opened half way. On bumpy roads, have the windows fully closed, or otherwise they will be jolted and harmed, and the car's inside will become dirty.
In long drives, stop periodically. You can make one drive of one hour and a halt all in one "go", but in a drive of two hours it's advised to take one brief brake. In a drive of over two hours, take breaks of ten minutes once every hour. This keeps you concentration levels high (and keeps children from harassing you, in family trips) and gives your tires and engine a short but precious cool-down.
Power steering is also something to take care of. The power steering pump has a problem when it is steered while the car is standing ("dry steering"), especially when the brakes are applied or when the steering motions are rapid. Another kind of damage can be caused by slamming the steering mechanism all the way to the "lock", and by keeping it fully turned. Here are a few ground rules:
- Steering smoothly, accurately and decisively. Further instructions as to how to steer around corners are found in my article about cornering.
- Don't "saw" the wheel back and forth: You are wearing the tires and steering linkages.
- Don't let the wheel return the straight based just on it's "realigning torque", use your hands.
- Don't slam the wheel all the way over. Also, when you do reach "full lock", ease the steering back slightly by a few degrees and you should hear the noise of the steering pump reduced.
- Try to park the car with the front wheels pointing straight.
- Try to avoid "Dry steering." If you must steer the car when it is stopped, try to do it with as little pressure on the brakes as possible (and preferably none) and without turning the wheel too rapidly.
- Don't hit curbs or go over them.
My last pieces of advice touch the subject of ending the drive and fueling the car. Try to avoid a situation where you are left with less than 1/4 of the gas tank filled. The gasoline functions as a coolant for the (expensive) fuel pump. This is even more crucial with diesel engines, where the compartment can absorb moist. When you finish driving a vehicle, slow down your pace gradually towards the end of the drive, shut down everything inside the car at that period of time and wait an extra ten seconds before shutting down the car (two minutes in a turbo-charger vehicle). Don't apply the throttle when you shut down the engine.
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