Energy Efficiency in Road Vehicles

Road vehicles constitute the majority of vehicles and they contribute greatly to the consumption of fuel resources which in turn lead to pollution of ambient atmosphere in substantial amounts. Therefore, the efficient use of fuel in road vehicles is very important both in respect of economy and environmental protection.

Over the years, the energy efficiency of passenger vehicles has increased dramatically. This depends on the voluntary decision taken by the vehicle manufacturing industry to technological improvements and to reduce CO2 emissions from new passenger vehicles. There has been no improvement in energy efficiency in road freight transport, partly due to low load factors. Trucks consume significantly more energy than rail or sea transport per ton-km. Sea and rail transport are seen to be more advantageous compared to the road. Nevertheless, the energy efficiency of rail transport has changed little in recent years and this shows us that there are still additional energy saving measures to be taken in the railway sector.

Due to the high population of passenger vehicles traveling in and out of cities, CO2 emissions contribute significantly to air pollution, apart from industrial, commercial and domestic facilities. Especially in cities, the emission rates of passenger vehicles at low speeds are quite high, and sometimes, in the case of reverse air currents, the city atmosphere makes it dangerous for human health. For this reason, reducing the fuel consumption rates of passenger vehicles as much as possible has a great proposition in terms of ensuring low CO2 emissions. However, from the other side, the drivers must also take into account some driving techniques, the physical condition of the vehicle and proper maintenance guidelines in order to economically drive their vehicles.

Our aim is to give advises to the drivers of the road vehicles; to reduce their consumptions on spare parts and consumable items as fuel, oil and other consumables throughout the lifetime of the vehicle by applying efficient driving and maintenance methods (mainly to be followed under the direction of vehicle producers) in order to achieve both economy in driving and efficient control of the air pollution with reduced fuel consumptions.

Practical Information for Economic Use of Passenger Vehicles

Planning of the Trip

Reduce the duration of your journey: The easiest way to save fuel is to reduce the time spent in the vehicle. Combine all your trips and jobs in a single journey to shorten your travel time. Be careful not to use your vehicle too much in the city, especially since the fuel consumption per unit km is too high. Walk short distances or choose public transport.

Avoid depart during heavy traffic hours: If you have the opportunity to travel outside the hours when the traffic is tight, you will not spend more time on the traffic and you will eventually consume less fuel.


Adjust and maintain the engine: A well-tuned engine can increase the fuel economy by 4 percent, so change engine oil on time and follow the advice given by the manufacturer about maintenance. The selection of the plugs in good quality and the replacement of the plugs within the time suggested by the manufacturer will affect the fuel economy very positively. Excessively sooted and platinum-melted plugs will exacerbate the fuel economy of the vehicle.

Use the right motor oil: Use motor oil in the quality recommended by the vehicle manufacturer. Fuel efficiency can be reduced by 1-2% by using a different motor oil than the engine oil recommended by the manufacturer. High quality engine oils can also help your vehicle's engine run more efficiently. Warning: The use of engine oil additives sold in the market is not recommended. In any case, it is very important to get a view of the engine oil maker before using them.

Check / change air filters: Air filters prevent debris from damaging the vehicle. Changing the clogged engine air filter helps to protect the engine cylinders and pistons while also positively affecting the fuel economy. The same refurbished air conditioner air filter also facilitates the operation of the compressor, preventing the air conditioner from pulling more power on the motors that drive it.

Check Tires / Change at the Right Time: The fuel consumption will increase as the tires of your vehicle wear out and the grip of your vehicle is reduced. Therefore, the use, maintenance and replacement of tires must be carried out taking into account the tire manufacturer's recommendations. As a common rule, tires should be displaced every 10 thousand km in front-rear diagonal. The tire must be replaced when the depth of the profiles on the tire's bottom surface is reduced to 1.6 mm and cracks are clearly formed on the tire's sides.

Check / correct the shock absorbers: The shock absorbers play a role in reducing the vibration transmitted from the tires on the vehicle. When the damping function do not come to full function with these shock absorbers, the vehicle vibration increases and at the same time the fuel consumption will increase due to the road contact which is interrupted more frequently than the ground.

Driving Techniques

Drive softer: Aggressive driving causes up to three times of fuel to be spent. Keep speeding gentle except departure.

Use high gears: High gears increase fuel efficiency in modern cars. Prefer gear as high as possible without forcing the engine. Particularly on departures, reaching high gears in the shortest time positively affects the fuel economy.

Keep your pace: Think ahead of time while driving. For example, instead of stopping completely in traffic lights, before you reach the lights, slow down a bit for the light or accelerate a bit before you enter an uphill slope with the acceleration and potential energy that the vehicle has gained.

Use Cruise Control: Use "Cruise Control" on long journeys. Cruise Control contributes to reducing fuel consumption.

Avoid excessive engine revs: Choose the right gear at the right time when your vehicle slows or accelerates. Do not let the engine speed gauge cross the "red line".

Avoid high speed: the faster you go, the more wind you meet with resistance, and your car will consume more fuel to go faster. Just cruising 10 km / h above the speed limit can affect the fuel economy by 23%.

Avoid running your vehicle at idle for a long time: Running your vehicle at idle will cause your vehicle to continue to consume fuel even though it can not move on. Switch off during the traffic congestion or while waiting. When you go downhill, take your vehicle gear as high as possible and do not run it at idle. Warning: It is extremely dangerous for vehicle and human safety to turn off the ignition or turn off the ignition when approaching the red light for the purpose of reducing fuel consumption. Progressing by closing the contact reduces fuel consumption but increases the risk of an accident incredibly. In such a case, while the power steering system has been deactivated then after several pumping cycles, the brake pedal's hardening may leave the driver helpless to stop.

Protect your distance from the vehicle in front: Leave a reasonable and safe distance from your vehicle to the vehicle you are following in front of you so that you can brake properly.

State of the Vehicle during Driving

Avoid overloading the vehicle: the surplus in the vehicle certainly increases fuel consumption. Remove unnecessary items from your vehicle. Especially when you go out on a long way, decide on the necessity of every item that is put in your baggage. Note: In addition to lightening the luggage, some drivers exaggerate this situation, loading 10-15 liters of fuel every time to avoid the additional weight disadvantage they consume extra fuel because of more frequent stop-and-go and increased tank losses at filling. In the meantime, there is also a lot of waste of time.

Remove the port baggage: Take care not to use the port baggage on your vehicle. If you have to use it, make sure you remove when you are not using it. These portbags affect the aerodynamic efficiency of your vehicle and increase fuel consumption by up to 5 percent by creating a pull back effect on your vehicle.

Keep your tires at the right pressure: Tires at the right pressure are safe and long lasting. A rubber blown less than 1 psi from the pressure the vehicle manufacturer recommends blows fuel economy. When the luggage is full and you are starting a long way, make sure that the pressure of your tires is not under the pressure recommended by the vehicle manufacturer.

Keep the windows closed: The wind entering from an open window will create resistance. To compensate for this, the gas pedal is pressed further and more fuel is consumed. When the sun-roof on top is left open while driving, aerodynamic pressure reduction on the roof during driving will brake and cause the rubbing of the vehicle to the ground and thus the fuel consumption will increase.

Use your air conditioner sparingly: the air conditioner puts extra load on the motor and uses your fuel to work. Ensure that the air conditioner is switched off in unneeded situations. In warmer weather, you can save money by using a fan instead of an air conditioner. Make sure that the ambient temperature inside the vehicle does not drop below 24 degrees when using the air conditioner. In addition, you will have a positive impact on fuel consumption if you deploy your air conditioner at certain intervals along the road or on road descents.

Check electrical consumption: The use of seat heaters and rear window heating in unneeded or unattended use can lead to increased electric current drawn from the battery, which can cause the electric generator to frequently switch on and increase the power drawn by the motor. This leads to an unnecessary increase in fuel consumption

Avoid refueling a small amount: some fuel evaporates each time you open the cover of the fuel tank. Avoid reloading your tank to prevent this. To minimize the evaporation from the reservoir cover, be careful to fill the reservoir during the late night time when the ambient temperature is cooler.

Modification in the Physical Structure of the Vehicle

Do not change tire sizes: Remember that fuel consumption will increase when existing tires on your vehicle are replaced with larger diameter tires or wider tires. In the first case, the vehicle's engine is exposed to more torque, and in the second, due to the tires, the friction surface, which is the vehicle's contact with the vehicle, increases the fuel consumption.

Do not install additional body kits: Body kits that you install on your vehicle afterwards can cause extra air resistance at the time of driving. Particularly front-mounted air crushers, while making the vehicle more stable, can cause more air friction and increase fuel consumption.

Do not change the exhaust system: Replacing part or all of the vehicle's original exhaust system may adversely affect the fuel economy of the vehicle. If a sports silencer is installed in place of the last and intermediate silencers, the combustion on the engine can become inefficient due to the deterioration of the air fuel balance entering the engine, which increases the fuel consumption.