Eco Driving

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Overview

In addition to external circumstances, such as weather, road conditions and congestion, driving behavior can considerably influence the vehicle’s fuel consumption. Being the operator of a vehicle, a driver can save a significant amount of fuel through economical driving (around 10% on average; around 20% can be achieved by comprehensive eco-drive training), and in the same moment increase road safety. Eco-Driving describes the application of techniques reducing fuel consumption and emissions which are affected by the behavior of the driver, without necessarily upgrading the vehicle’s technology.

This article outlines benefits and concrete principles of Eco-Driving which can be adapted regardless of the vehicle type and the implementation of specific Eco-Driving tools and initiatives.

Benefits

Besides the above mentioned advantages of fuel savings and increased road safety, Eco-Driving leads to following advantages:

• A reduction of variable costs (fuel, repairs, tires, maintenance system)
• An increase of effectiveness (less down time due to repair works and maintenance)
• A decrease of negative environmental impacts
• A decrease of insurance costs due to fewer accidents from less aggressive driving
• Stress reduction for drivers, passengers and fellow road users.

Principles

The points below summarize the most important principles when it comes to Eco-Driving. They are independent from the car type and trip purpose.

Prepare Your Vehicle before you Drive

Drivers need to ensure that their vehicle is checked carefully and safe. In commercial transport, maintenance usually takes care of this.

However, drivers are also in charge of regular basic checks, including the following points:

• Fluids: engine oil, coolants, screen wash
• Tires: check for rips and stones, tire pressure, spare wheel
• Braking system: check pressure and pressure drop, bleed off condensation water
• Lighting and mirrors: check and clean as required

Start and Move Off Moderately

When starting the engine for the first time of the day, the driver should allow it to run at a moderate speed until the correct oil pressure has been built up. A cold engine wears faster than a warm engine, particularly at high engine speeds. This is due to the fact that pistons and cylinders are designed to fit best with a warm engine. A VTL study has shown that driving with a cold engine requires approx. 15% more fuel than driving with a warm engine, and a gentle driving style brings the engine to its operating temperature much more rapidly. After about 30km (depending on external factors), an engine is properly warmed up.

When stopping a vehicle for more than one minute, e.g. at the traffic light of a big intersection, a driver should turn off the engine of the vehicle in order to save fuel.

Drive the Modern Way and Think Ahead

Aggressive driving wastes fuel, wears out the engine, tires and brake pads which results in higher maintenance costs for the car owners. Sensible driving, looking ahead as far as possible, anticipating the surrounding traffic, avoiding unnecessary braking and accelerating belong to a modern driving style and will enable the drivers to contribute not only to their own health but also to the environment. Driving at a constant road speed as often as possible can further contribute to energy savings, as braking and accelerating consumes much more fuel than keeping a constant speed.

Drive in the Highest Gear Possible

When starting off, drivers should engage second gear once the vehicle has moved through its own length and feel free to skip a gear when changing up if the traffic situation is suitable. Driving 50 km/h in 5^th gear is unproblematic for today’s vehicles, and drivers should always select the highest gear possible. As long as the car runs smoothly and acoustic comfort is maintained, the engine speed is not too low. Driving in this behavior will significantly reduce noise pollution and fuel consumption. Drivers of cars with automatic gearboxes can save fuel by avoiding the kick-down feature and briefly taking the foot off the accelerator. The automatic gearbox will then shift to the next higher gear.

Use Engine Brake

By letting the vehicle roll and use its momentum while still in gear the fuel supply to the engine gets interrupted and no fuel will be consumed. The best time to apply this method is when the driver can also benefit from the braking effect of the engine (i.e. on a downhill gradient or when approaching a red traffic light). Another benefit regarding fuel consumption can be reached by disengaging the clutch. This is particularly effective if coasting, e.g. on a long stretch of road is possible (naturally without obstructing following traffic). Coasting downhill is also useful, but only if the gradient is not to steep.

Use Auxiliary Equipment in Moderation

From the cigarette lighter to the defroster, any in-car device that runs on electricity uses power from the battery. The battery is recharged by the alternator, which in turn is powered by the engine. Subsequently, the engine burns more fuel if more electricity is being used. The air conditioner is particularly costly to run. It refrigerates air via the compressor, which takes power directly from the engine and then circulates in the car by means of an electric fan run by the battery. On a hot day the air conditioner can increase fuel consumption by up to 25%. A damaged or leaking air conditioner will increase this value even more. Yet the temperature (and fuel consumption) can also be reduced by airing the vehicle before the journey and driving off with open windows for a short time to let the heat escape. Seat heating and a rear window heater also consume fuel. Therefore the heating should be switched off as soon as the rear window is clear and the seats are warm. During the journey, drivers can check and re-check the equipment they are currently using and whether they really need it.

Check Your Tire Tread and Tire Pressures

The tire tread transfers forces between the vehicle and the road surface, carries off water and contamination and cools the tire. Besides legal requirements regarding the depth of the tread, proper maintenance also results in a higher driving comfort and safety as well as a lower fuel consumption.

Under-inflated tires increase “rolling resistance”. A low tire pressure requires more energy to push the car forward and results in a higher fuel consumption. Rolling resistance can account for up to 15% of the overall fuel consumption. Checking the tire pressure of vehicles saves fuel and has to be done before the car sets off. If the tires are inflated to the recommended tire pressures for a full load (the figures will be found on the fuel filter flap), rolling resistance will be lower and so will be the consumption. When purchasing tires, car owners can look out for those with the lowest possible rolling resistance. In addition to 3% extra fuel savings they are also less noisy.

Besides the general maintenance, drivers should also be aware that the driving style influences the lifetime of a tire. Heavy breaking and acceleration, overloading and inaccurate wheel alignment will decrease the tire life and besides the negative environmental and safety factors resulting from these driving styles lead to higher costs for a frequent tire renewal.

Avoid Short Trips

Cold engines use most fuel. Many short trips can raise the fuel consumption as high as 30l/100km. However, if drivers take care of several errands in one trip, the engine is more likely to reach the required operating temperature and will consume less fuel. However, leaving the engine running to warm it up does not reduce consumption, but increases it.

Remove Roof Rack

A good aerodynamic shape is the key to low fuel consumption, particularly at high speeds. Roof-attachments such as cycle racks and roof boxes nullify the advantage of a beneficial aerodynamic shaped vehicle. A 33% rise in aerodynamic drag will increase fuel consumption by as much as 2l/100 km at 160 km/h. Removing the roof rack makes a lot of sense if it’s not needed, for example between two skiing or mountain bike weekends. The car’s aerodynamic advantages can easily be restored for day-to-day trips when following this principle.

Avoid Unnecessary Weight

Every kilo of luggage costs more fuel. To be precise: a weight of 100 kg can increase fuel consumption by up to 0,31l/100 km. Contents of the luggage compartment should be inspected on a regular basis. With today’s network of filling stations keeping a full fuel canister in the car is no longer needed. Nobody needs more than one road atlas and the bag with the golf equipment doesn’t have to be carted around all year – neither does the picnic basket in winter or the can of antifreeze in the summer.

Implementation and Tools

Implementation

Understanding more about the advantages of Eco-Driving helps to identify important areas in order to make Eco-Driving effective and sustainable. These areas include:

• Making it easy – and cheap – to get started on Eco-Driving
• Showing fuel saving potentials to drivers
• Engaging drivers over time to maintain the changes, beyond their initial exposure to Eco-Driving tips or training
• Working with efficient car technology in a complementary way

Due to the known environmental and economical advantages of Eco-Driving, an increasing amount of courses regarding the topic are being offered in countries around the world, especially for drivers of commercial vehicles. However, also private car owners can sign up to one of the various classes offered by car manufacturers, automobile clubs, driving schools, environmental organizations or NGOs, and download reading material regarding main techniques for an efficient driving style.

It is further important to raise public awareness about the topic on all levels, which can be done through different types of advertisement on various channels. In Germany, it is also a requirement for driving schools to include the topic of Eco-Driving in the education for young drivers.

On top of offering classes for their employees, companies also have to set the right incentives for their drivers in order to achieve fuel savings for their vehicle fleet. Monetary incentives should be given to the drivers for fuel savings through an adapted driving style, e.g. when their fuel consumption is below the companies’ average fuel consumption. Incentives can also be provided to drivers who didn’t have accidents for a longer time period, however monetary incentives have proven to be the most effective way to assure sustainability.

Eco Driving Tools

Although changes in driving behavior can already lead to significant results, additional measures will even increase fuel savings and thus lead to further co-benefits. So-called ‘Eco Driving Tools’ have been developed in different countries in order to achieve cost savings when driving, and give a live visibility of the impacts of individual driving behavior.

These approaches are predominantly targeted at bus and truck drivers but also at owners of private vehicles. There are different approaches of eco driving tools existing on the market. First of all eco driving tools are offered for different vehicle types, which are used for private or commercial purposes. Private passenger cars, trucks/buses and corporate fleets cover most important fields of use for eco driving tools. On the level of implementation, eco driving tools are available in many different application types. From simple eco-drive trainings, which can be real or simulated trainings, up to software based tools (i e. for PC or Smartphone), hardware based tools (i.e. On Board Units) or even a combination of both (software and hardware based tools). A more comprehensive overview can be found in a the article: Eco Driving Tools.

Further Information

• energypedia - All Transport Articles
• EcoMobility
• Eco Driving Tools

References

• GIZ Sourcebook 'Eco-Driving'
• China Daily (2010-11-06)
• Fiat Group Automobile UK Ltd.