eco-driving advice

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This guide will give the reader a good insight into the concepts and principles of eco-driving. (1) It presents several easy-to-understand fuel-saving strategies that any driver can follow to obtain quickly a significant and rapid improvement in fuel economy. It aims to offer benefits for drivers of private cars, company cars, trucks and buses. In addition, it is worth remembering that reducing fuel-consumption has a direct and positive influence on the reduction of vehicle emissions, whilst at the same time saving money. With the right driving style drivers can save an average of 5-10% on fuel, and in several cases as much as 20%.

The strategies presented below are divided into two main groups: before you set off, and on the road. While the former are strategic and tactical procedures to be performed before your journey, the latter are changes to your driving behaviour which you can follow but only in strict compliance with traffic safety regulations, because energy efficiency should never take precedence over road safety. Finally, we need to remember that cars are different from one another, and so their fuel-consumption and emissions are dependent upon many factors, including vehicle-related factors such as model, size, fuel type, technological equipment and mileage, and operational factors such as speed, acceleration, gear selection, road gradient and ambient temperature. As a result of these different factors, what any one driver can obtain by applying the proposed strategies will vary enormously, and in the worst case produce no gains, even when comparing two similar vehicles. For these reasons your best strategy is to try and understand the principles and advantages behind each strategy rather than focus on percentages and figures.

Disclaimer: For reasons of safety you need to bear in mind that the suggestions we give are only examples of recommendations for saving fuel, and that they are in no way rules which must be observed slavishly. Drivers must only ever drive in a way which keeps them and other road users safe, always paying due heed to the Highway Code, and only applying the hints and strategies we suggest having taken into account the prevailing road conditions, traffic, weather and so on.

Before setting off:

Tyre pressures and wheel alignment
1. Check tyre pressure at least once a month and keep the tyres inflated as detailed in the car's handbook, always bearing in mind the kind of journey you are about to undertake. In addition it is better to check tyre pressure when the tyres are cold. Moreover, driving with under-inflated tyres is unsafe because of the negative effect this has on road-holding and braking.
2. Pay attention to the wheel alignment to minimize as much as possible the rolling resistance caused by poorly aligned wheels. If you notice that your car is pulling to one side and no longer travelling in a straight line you should have your wheel alignment checked, as this is a sure sign that there is problem with your steering geometry.
Be kind to your vehicle
1. Make sure your car is running efficiently by following the manufacturer’s service schedule as detailed in the handbook.
2. Keep the air-filters clean: with dirty and clogged air-filters the engine is not able to run at peak efficiency, and a less efficient engine is wasting fuel needlessly. A visual check to the air-filters is enough to tell you if they must be replaced or not, and in addition the appropriate replacement intervals are recommended in the car's handbook.
3. Always use the correct engine oil choosing a good quality brand with the viscosity grade recommended in the car's handbook. Using worn-out oil, or oil with the wrong specification can increase fuel-consumption.
Plan your trip
1. plan ahead to combine journeys and to perform more errands at the same time; schedule your journey to avoid peak traffic hours. This will not only reduce the amount of driving you have to do, but will also enable you to avoid congested routes, leading to less idling and reducing stop and start travel. In addition, short trips (of less than 3 miles or 5km) are the most polluting and fuel consuming because they do not allow the engine to reach its peak operating temperature.
Minimize the payload and air resistance of your vehicle
1. Remove any unnecessary extra loads from your car because a lighter car has a lower rolling resistance factor. In fact, the power needed to overcome rolling resistance caused by the vehicle’s weight is approximately proportional to its speed, which means that the energy required to move the vehicle grows steadily as speed increases. In addition, smaller cars are more affected by additional loads.
2. Keep the vehicle’s roof free, removing roof racks and other bicycle, ski or luggage racks when not required, because these reduce the aerodynamic quality of the car. An aerodynamic car has less air resistance, and it is a fact that the energy required to overcome air resistance increases approximately with the cube of the car’s speed.
Join a car pooling community scheme
1. drivers can publish their journey schedule on specific websites well in advance in order to find passenger(s) to share their journeys. By doing this more than one person will travel in the car, which has advantages both for the environment and for the drivers themselves, since drivers contribute to reducing the number of cars on the roads while at the same time recovering part of their travel costs.

On the road:

Change gears appropriately
1. always drive with the engine running at the correct engine speed (rpm), changing to a higher gear as soon as possible. The revolution counter is a useful guide to help you decide when to change gear. For most internal-combustion engines fuel economy is a function of speed divided by engine revolutions: the engine is working at peak efficiency when delivering the greatest amount of power with the lowest possible fuel consumption. This is reached when the engine is running at the right number of revolutions per minute (rpm) which is around 1800-2500 rpm for petrol engined cars or 1500-2000 rpm for diesels. However the optimal engine speed varies with different engines and according to traffic and weather conditions; more precise information can be found in the car's handbook.
Anticipate traffic flow
1. Try to avoid areas with heavy traffic. This will allow you to minimise the number of times you stop and start, and also to maintain a steady speed. Driving as steadily as possible will cut down on energy wastage and reduces fuel consumption.
2. Maintain a safe distance between vehicles, avoiding harsh braking by leaving enough room between you and the car in front. This distance is not a fixed length but changes according to your current speed: the higher your speed, the greater the stopping distance required.
3. Read the road ahead to avoid unnecessary acceleration and deceleration. For example, but only if it is safe to do so, you can avoid unnecessary stopping and starting by slowing down as you approach a red traffic light in order to arrive at the junction just as the light changes to green. In general, you should always try to anticipate the behaviour of other road users to allow yourself more time to brake or accelerate gradually.
Switch off the engine, even during quite short stops:
1. switching off the engine even for a short period is worthwhile, as it decreases fuel-consumption and CO2 emissions. For instance, waiting with the engine idling at a railway crossing for just 20 seconds uses more fuel than restarting the engine. But this energy efficiency strategy must never prevail over traffic safety, however: the engine should only be switched off under the right circumstances and only when it is safe to do so.
Open windows and air conditioning
1. You need to know under what circumstances one is more appropriate than the other.
  1. Open windows decrease the aerodynamics of the car and increase air resistance. Opening the window has a negative effect on fuel-consumption which steadily increases with speed. Moreover, at higher speeds, open windows are very noisy.
  2. Air conditioning increases the effort required by the engine, which in turn leads to an increase in fuel-consumption just to maintain the same speed.
  3. However, when deciding whether to turn off the air-con or to open the windows, the best strategy is that, at higher speeds, you are better off if you close the windows to cut down on aerodynamic drag and use the natural ventilation of the car, if possible without the air-con, whilst, at lower speeds, it makes sense to open the windows.
Drive at the most efficient speed
1. good driving is eco-driving. Many cars now have an on-board computer which can help you find the speed at which your car has the lowest possible fuel consumption. Once you know this, you should aim to travel as much as possible at this optimum speed. For many cars this is in the 25-40 mph range (40-60 km/h), so if you are not in a hurry, why not be an eco-driver rather than a racing driver?

If you wish to contribute further ideas, however small, or to ask for more detailed information or even to point out any errors you may find, please let us know by emailing project@integreen-life.bz.it