In the last decades, engine technology and performance of passenger cars, lorries and buses have improved rapidly, however, most drivers have not adapted their driving style. Ecodriving is adapted to modern engine technologies and means smooth and safe driving at lower engine revolutions. Ecodriving is easy to learn and it has been shown that written information itself has a substantial impact on driving behaviour, on safety and on fuel consumption without increasing travel time.

There are five basic rules to follow.

    * Shift up as soon as possible
    * Maintain a steady speed
    * High gear and low engine RPM
    * Anticipate traffice flow
    * Decelerate smoothly

Shift to a higher gear

Shift up between 2.000 and 2.500 revolutions. For both petrol and diesel fueled cars.

Part of the power of a passenger car's engine is lost by internal friction. These losses increase with engine speed. By driving at low engine speeds these losses remain limited, which reduces fuel consumption. The efficiency of a car engine also increases when a high engine load is used (giving more gas at low engine RPM (revolutions per minute)). Under these conditions the engine power is generated more efficiently. During acceleration the most efficient way of driving is therefore to shift up as soon as possible (at low engine speed) and to apply a relatively high load on the engine. Driving in a high gear automatically requires a high engine load to keep up with traffic.

In order to use the efficiency of a car engine in an optimal way, a maximum engine speed of 2500 RPM for shifting is recommended for petrol/LPG engines. Because diesel engines generally reach their optimal efficiency at lower engine speeds, a maximum engine speed of 2000 RPM for shifting is recommended. A rev(olution) counter is a useful aid to determine the right shifting moment. The shifting recommendation is anyhow applicable to cars with a manual gearbox, but it can also partly be applied by cars with an automatic transmission (see 'cars with an automatic gearbox). The recommended way of shifting is in no way harmful to a properly maintained engine.

Maintain a steady speed

Maintain a steady speed, using the highest gear possible!

When accelerating, energy in the fuel is used to propel the car. Part of this energy is wasted when you brake. You may experience this phenomenon after hard braking; the brakes have become very hot because of the transformation of propulsion energy into heat. Therefore, repeated acceleration and braking requires a lot of energy (fuel).

This can also be explained by the fact that the average car only needs 5 kW of power to drive at a steady speed of 50 km/h (at 120 km/h the amount of power needed increases to approximately 25 kW). The remaining 90% (or more) of the engine's power is only needed for acceleration or for driving at very high speeds. By driving steadily as much as possible, the wastage of energy and fuel remains limited. Try to avoid unnecessary acceleration and braking. Cruise control is a useful aid for smooth and steady driving.

Driving at steady speed not only increases fuel-economy, but it also has a positive effect on exhaust emissions, traffic safety, traffic flow and passenger comfort.

High gear and low engine RPM

As already mentioned, the power needed to drive at a steady speed is rather low. Therefore, a high gear can be engaged without any problem at low engine speeds. This saves fuel and is in no way harmful to the engine, when it is properly maintained

The opinion that the accelerator pedal is directly fixed to the fuel consumption is incorrect for a petrol engine. The accelerator pedal operates only the throttle/ butterfly valve and consequently definitely only the air quantity. On the basis of this position and also other influences such as the momentary revolutions, the fuel quantity used is calculated by the engine. Each small reduction in the level of revolutions means that less fuel is needed.

Anticipate traffic flow

Look ahead as far as possible and anticipate to surrounding traffic!

In order to drive at a steady speed (as discussed in recommendation 2), it is important to anticipate to surrounding traffic to avoid unnecessary braking and accelerating. For example, when approaching traffic lights, when overtaking traffic like cyclists or agricultural vehicles or when driving on a busy highway, anticipating to other traffic can have a big influence on how steadily you drive.

Many situations can already be noticed far ahead, long before approaching the situation itself. In case you use cruise control (see recommendation 2) you will have to anticipate even more to be able to make full use of its benefits.

Decelerate smoothly

When you have to slow down or to stop, decelerate smoothly by releasing the accelerator in time, leaving the car in gear!

Petrol and diesel cars manufactured from 1990 onwards, are generally equipped with fuel injection combined with an electronic function that cuts off the engine's fuel supply under engine braking (accelerator released and a gear engaged). The advantages of this fuel cut off function can be used by releasing the accelerator in time, for example when approaching traffic lights. This also reduces wear and tear on the brakes, reducing maintenance costs. Engine braking, not only has a positive effect on fuel consumption, but also on exhaust emissions, traffic safety, traffic flow and passenger comfort.

In case of less modern cars with a carburettor and older diesel cars (generally manufactured before 1990), it makes no difference whether you decelerate with gears engaged or disengaged, for the carburettor is a mechanical device that is not equipped with electronics to cut off fuel supply. These cars consume an equal amount of fuel under engine braking and when idling. However, releasing the accelerator in time still avoids hard braking and improves the durability of the brakes.

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