Every driver eventually starts wondering how much fuel their car consumes and compares actual figures with those stated in the documentation. As we have already mentioned, the figures in the passport are a rather conditional concept. When the actual consumption starts to noticeably increase, the car owner looks for ways to reduce fuel costs and save their budget. This material will discuss what factors provoke excessive consumption and how to deal with them.
Understanding the causes of increased fuel consumption
All the reasons why a car starts to consume more fuel than stated by the manufacturer or than was usual during operation can be divided into two categories: technical and those related to the driver's actions.
Technical reasons are malfunctions of various components and mechanisms that wear out, break down, and cease to fully perform their tasks over time.
Subjective reasons are related to the human factor: driving style, overloading the car, installing additional equipment, and the like.
Among the most common technical malfunctions leading to increased consumption, the following can be highlighted:
1. Incorrectly set ignition. Even if the ignition timing is shifted by just one degree, fuel consumption can increase by 1%. The greater the deviation, the more noticeable the excessive consumption.
2. Incorrect spark plug gaps. If the distance between the spark plug electrodes is disturbed, they begin to work intermittently. On average, this adds about 4% to consumption.
3. Insufficient coolant temperature. When the coolant does not warm up to the required values, the engine spends more fuel on warming up. Excessive consumption can reach 10%.
4. Wear of the cylinder-piston group. When the parts of this system fail (often occurring at high mileage or when using low-quality fuel), consumption noticeably increases.
5. Wear of the crank mechanism. Reduced compression due to worn rings, pistons, or cylinders leads to loss of power. To compensate for this, the driver has to press the gas pedal harder, which increases the engine's appetite.
6. Problems with the clutch. If the clutch slips, the driver is forced to rev the engine more often, which directly leads to excessive consumption.
7. Wear of the gas distribution mechanism. Disturbance of valve clearances, wear of the belt or chain, as well as other elements, leads to depressurization of the cylinders. Pressure drops, the engine loses power and begins to consume more fuel.
8. Disturbance of camber and toe angles. Incorrect wheel geometry provokes skidding, rapid tire wear, and deterioration of handling, which ultimately affects fuel efficiency.
9. Insufficient tire pressure. Deflated wheels increase rolling resistance. For example, if the pressure drops from 2 to 1.5 atmospheres, consumption can increase by 3%. Moreover, even if only one wheel is deflated, this will already affect fuel consumption.
10. Clogged air filter. If the filter is not replaced in time, for example, during scheduled maintenance, it will begin to impede the flow of air necessary for normal combustion of the mixture. The result is increased consumption.
11. Faulty thermostat. If the thermostat is stuck in the open position, the engine, especially in winter, does not warm up to operating temperature, which leads to excessive consumption.
12. Dirty injectors. Resinous deposits on the nozzles, which appear when using low-quality fuel, disrupt sealing and atomization. Fuel burns inefficiently, which increases its consumption.
13. Malfunctions in the operation of electronic sensors. If the throttle position sensors, air flow sensors, or oxygen sensors transmit incorrect data, the control unit prepares the wrong mixture — too lean or too rich. This leads to loss of power and excessive consumption.
Subjective reasons affecting fuel consumption include:
1. Overloading the car. The heavier the car, the more fuel it consumes. Every additional 100 kg increases consumption by 10%. A loaded roof rack adds up to 40%, and an empty one about 5%. The exact figures depend on the design of the rack, its aerodynamics, and driving speed.
2. Open windows. At speeds above 50 km/h, lowered windows worsen aerodynamics, which can increase consumption by an average of 4%.
3. Sharp accelerations and braking. Aggressive driving style forces the engine to work in a stressed mode, which leads to significant excessive consumption.
4. Additional tuning. Installing body kits, spoilers, and other elements not provided by the factory disrupts the car's aerodynamics and increases its "appetite."
5. Operation of the audio system and air conditioner. A noticeable share of fuel is spent on powering these systems. An air conditioner running at full power can increase consumption by 15%, and constantly turned-on multimedia by 7%.
6. Inappropriate oils and fluids. The manufacturer does not accidentally recommend a certain viscosity — it is selected through testing. If, for example, a more viscous oil is poured, consumption can increase by 10-15%.
7. Operation of headlights. Low beam increases fuel consumption by about 5%, high beam by 10%.
Eliminating the causes and bringing consumption back to normal
Having figured out the main causes of excessive consumption, let's move on to ways to eliminate them. Let's start with technical problems.
1. To adjust the ignition, it is better to contact a service center where the correct ignition timing angles will be set using a diagnostic scanner and a strobe light.
2. Spark plug gaps can be adjusted independently using a special tool with feeler gauges. First, you need to measure the current gap with a wire gauge, and then, if necessary, correct it. If the necessary tools are not available, it is better to contact a service station.
3. Problems with coolant temperature may be related to depressurization of the system. It is necessary to check it for leaks and replace worn elements. It is also possible that the fluid itself has already served its service life (usually about 3 years or 60 thousand kilometers) and requires replacement.
4. If the pistons, rings, or pins of the cylinder-piston group are worn, they need to be replaced with new ones.
5. Worn parts of the crank mechanism, such as main and connecting rod bearings, also require replacement.
6. A failed clutch, as a rule, is not repaired — it is replaced entirely.
7. Before repairing the gas distribution mechanism, it is necessary to conduct diagnostics to accurately determine the cause of the malfunction. Then the mechanism is disassembled and worn parts are replaced. This work is best entrusted to service station specialists.
8. Camber and toe adjustment must be carried out on a specialized stand at a service center. Without special equipment, it is impossible to do this correctly.
9. Tire pressure should be checked regularly, preferably at every refueling, and wheels should be inflated in time. If the tires are worn or the valve is faulty, they need to be replaced. It is also worth considering installing tires with low rolling resistance.
10. The air filter is best replaced with every engine oil change. Its service life also depends on operating conditions: the harsher they are, the more often replacement is required.
11. If the thermostat is faulty, it needs to be removed (after draining the coolant) and the operation of the valve checked. If it sticks, it is worth trying to clean it from contaminants. If this does not help, the thermostat will have to be replaced.
12. Contaminated injectors require decarbonization. This can be done using special fuel additives or by contacting a service station where flushing is performed with special fluids under pressure.
13. Diagnostics of the sensors of the electronic engine control system are carried out using a computer scanner. Based on the diagnostic results, the faulty sensor is identified and repaired or replaced.
It is easier to cope with subjective reasons — it is enough to follow a few rules.
1. Do not overload the car beyond the permissible weight. If the roof rack is rarely used, it is better to remove it.
2. Do not open the windows fully — it is better to leave a small gap for ventilation and only for a short time.
3. Try to drive smoothly, without sharp starts and braking. Shift gears in time, use coasting and engine braking.
4. If possible, refuse to install body kits, spoilers, and other elements that worsen aerodynamics.
5. Do not overuse the multimedia system. Try not to turn the air conditioner on at full power, especially in the city. On the highway, the power draw on the compressor is less noticeable, but when overtaking, it is better to turn off the climate control.
6. Use oils and fluids with the viscosity recommended by the manufacturer.
7. No one uses high beam constantly, but low beam from October to May will be mandatory according to the new rules. It will not be possible to avoid excessive consumption in this case, but you can install LED daytime running lights, which consume less energy than conventional lamps.
Summary
As can be seen, fuel consumption is influenced by many factors — both technical and related to driver behavior. To avoid watching fuel quickly disappear from the tank, it is worth regularly checking the main components of the car and following recommendations on driving style. It is important to remember: if several factors act simultaneously, their influence is not directly summed up. For example, when driving with open windows, low beam on, contaminated injectors, and a loaded trunk, consumption will not increase by exactly 60% — the final figure will depend on the degree of injector contamination, the weight of the luggage, the operating time of the headlights, and other conditions.
It is worth noting that this material is informational and recommendatory in nature, and all the figures given are averaged.
