Why is the car eating a lot of gas?

A headache for a motorist is high gas mileage. Prices at gas stations are regularly increasing, so you have to spend more and more on fuel from the family budget. Although sometimes it is enough to give your iron horse a couple of hours to diagnose with easy repairs, and this time will return in the form of saved liters per hundred kilometers.

Of all the consequences that affect the parameters of efficiency, it is customary to single out two main reasons for high fuel consumption:

  • direct (poor performance of individual nodes or elements, as well as their complete failure from the working state);
  • indirect (factors are not directly related to structural changes in the process of operation).


  • 1 Structural causes of consumption
    • 1.1 Lambda probe
    • 1.2 Candles
    • 1.3 Filters
    • 1.4 Electrical part
    • 1.5 Catalysts
    • 1.6 High idle
    • 1.7 Lead angle
    • 1.8 Mass air flow sensor
    • 1.9 Nozzles
    • 1.10 Compression
  • 2 Operational reasons for consumption
    • 2.1 Driving style
    • 2.2 Car class and engine size
    • 2.3 Terrain
    • 2.4 Automatic transmission
    • 2.5 Injection systems
    • 2.6 Fuel quality
    • 2.7 Season
    • 2.8 Four-wheel drive
  • 3 Additional factors
  • 4 findings

Structural causes of consumption

To identify such faults, it is possible in some cases to independently conduct a visual diagnosis, and then turn to professionals.

The Lambda probe

The failure of the oxygen sensor in most cases occurs due to the use of leaded fuel. The remains of lead oxides cover the working part of the site. In this regard, the injectors begin to add more to the fuel mixture of gasoline. This chain leads to an increased level of CO in the exhaust gases. Often it is for this indicator that one can find out that the lambda probe needs to be changed or repaired.

what are the reasons for high fuel consumption

Lambda probe location

Computer diagnostics of the engine is also able to reflect the inoperative sensor. In this case, you can simply replace it with a new one. However, this is quite an expensive action.

The approximate cost of a new original lambda probe for a Japanese foreign car will be about $ 400.

A cheaper option for such a repair is to replace the assembly with a “Boshevsky” sensor, which is a spare part for VAZ vehicles.


Low-quality gasoline adversely affects the operation of the spark plugs in the engine. Replacing them with new ones will help in the fight to reduce fuel consumption. But when buying a kit, you need to check for the presence of a properly established clearance.

how to reduce the causes of high fuel consumption

How to identify substandard candles

After all, even in the company stores, suppliers may have low-quality goods. Then the purchase will be useless. The price of some products can go up to $ 40 apiece.


To overcome the increased fuel consumption will help compliance with the regular maintenance of the car. During this procedure, it is advisable to check the replacement of all filters required for this period of operation:

  • oil;
  • fuel;
  • air.

You should not expect a big return from this action, but the positive effect will be noticeable.

Electrical part

Due to contamination of the distribution switch or high-voltage wires, there may be electricity leaks. This affects the quality of burnout of the fuel mixture in the cylinders. Incomplete combustion occurs. Therefore, you can check the electrical circuit for the presence of breakdowns. In case of obvious contamination, it is possible to clean or partially replace damaged armored cables.


This element of the fuel system helps to combat air pollution. But at the same time the car loses a little in power.

how to eliminate increased fuel consumption

Catalyst appearance

If the catalyst is defective or not at all in its place, then this may also be the reason why the car eats a lot of gasoline.

See also: German car brands: a detailed list with photos

High idle

Improper adjustment of the idle speed level contributes significantly to the flow during warm-up, as well as when the car is stopped with the engine unplugged.

For stable operation of the power unit, it is necessary to clearly set the speed set on the mat.

Lead angle

More experienced drivers also indicate to beginner colleagues that the ignition timing has been correctly adjusted. A signal to this can serve as unstable work at idle, and the problem with starting the car. If these symptoms occur regularly, then you will need a little intervention in the adjustment of the distributor.

Mass air flow sensor

An important element of a modern car is the fuel consumption sensor. Its function is to control the mass of air that is fed to the engine.

how to get rid of increased fuel consumption

How does the mass air flow sensor

From the correct ratio of fuel and oxygen, we get maximum efficiency in gas mileage and car power.

If there is over-enrichment of the mixture, then this affects the greater fuel consumption.


Contaminated injectors do not spray fuel in the combustion chamber. More often it just flows for enrichment. To avoid this you will need to flush this part of the injector. This work is performed on specialized stands in the service station or at home.

The regularity of this procedure depends on the quality of the fuel used.

In Russian reality, the interval between maintenance should not be done more than 10 thousand kilometers. If the budget allows you to make a replacement, it will be better to install new kits.


To check this parameter, you need a special device - a compressometer. It is advisable to have it in the garage to check the compression in the cylinders. The approximate cost of the device is 10-15 dollars.

how to reduce high gas consumption


Working with him is easy. It is enough to unscrew one of the spark plugs, and in its place to screw the threaded fitting of the device. There is an option with a rubberized tip, but they need an assistant to hold the measuring device in the desired position by force. The check is done in all cylinders.

The deviation between all readings should not be significantly higher than 10%.

The exact level of standard data can be found in the passport cars. If it is significantly different from empirical measurements, then elimination of this defect is required. For example, for VAZ 2112 this indicator should be 12.6 kgf / cm2.

Operational reasons for consumption

Breakdowns and failures are not the only causes of increased consumption. They are often visible even to the owners or are diagnosed by service centers specialists. But there are not all the signs can be identified by workers of service stations at their stands. We have to independently analyze and understand the essence of the process.

Driving style

All drivers vary in driving style. For a quiet driving style, without jerks and sudden accelerations / braking, moderate and sometimes economical fuel consumption is typical.

what causes the high fuel consumption

Winter ride on all-wheel drive SUV

If the driver often uses a sharp depressing of the accelerator, then the car cannot do without an unnecessary expense.

“Jerk” at the traffic lights is possible, if the engine power allows. But at the same time, the consumption will “rush” to the sky-high 30 liters of a passenger car. Should I use this style of behavior on the road, everyone should make their own decisions.

Car class and engine size

It is believed that for the increased volume of the engine owners often pay a significant fuel consumption. This is a kind of tribute for comfort. A car of the same class, weight and brand, should have less consumption, but in practice this formula is not always confirmed.

A massive power plant spends less gas on a speed or power result than a similar car with a reduced engine.

This is due to the fact that the "small" engine is working with a large load. And accordingly will spend more fuel.

See also: What is the VIN-code of the car


The parameter is relevant for hilly and mountainous areas. If the car was initially operated in flat terrain, then he had one expense. If you change the road conditions (frequent traffic jams, a lot of lifting sections), the flow rate may change upwards.

Automatic transmission

The opinion that the automatic transmission increases fuel consumption by 10-15% is often confirmed in practice. In some cases, the "increase in gluttony" can be 1-2 liters per 100 km. Sometimes the difference is almost imperceptible. It also depends on the machine itself, and not on just having it. After all, older models with four steps differ from the six-speed automatic transmission.

what are the reasons for high fuel consumption

Box "automatic" or "mechanics"

To save when driving with such a unit, it is possible to recommend the use of the mode of the high gear when driving outside the city.

OverDrive reduces consumption and helps not to reduce speed. When driving a city, the owners' reviews are not so clear. The characteristic of the option becomes clear to a greater extent in individual experiments.

Injection systems

The sensitivity of direct injection fuel systems (D4, GDI, etc.) to poor-quality gasoline is felt almost from the first days of the operation of the machines. Some automakers do not even officially deliver cars with a specific motor configuration to Russia. This is justified by the high cost of maintenance and repair when using low-grade fuel.

how to identify the causes of high fuel consumption

Fuel injection system

Therefore, when choosing and before buying a used foreign car, it is advisable to inquire about its fuel characteristics. A relatively low price for a nice car can result in very expensive repairs.

Fuel quality

Not all gas stations sell the same gasoline. Unfortunately, this fact also affects the flow. In 95 may be an excessive amount of additives. Therefore, a banal conclusion - to fill in fuel only at proven gas stations. Although the presence of a corporate logo is not always a sign of quality. You have to trust your own experience.


Beginners need to be reminded that when operating a car in the winter, there will be more consumption. It affects not only the "stove", ice and traffic jams. The machine starts with a cold engine, which consumes the first re-mixed mixture. Also, due to cold oil, whose properties change at low temperatures, the power plant requires a little more power to rotate the shafts.

Four-wheel drive

A car with one driving axle will be more economical.

Fans of all-wheel drive should immediately prepare for increased fuel consumption.

Or, if possible, do not include all drive wheels in unreasonable situations.

Additional factors

Consumption can rise slightly due to the power take-off from the engine when electric appliances are in operation. The list has an audio system, air conditioning, included headlights, electric power steering. It is also advisable to change winter tires in time. Driving on the highway on off-season wheels can also take away fuel. It also happens the usual theft with incorrectly calibrated meters at gas stations. But it happens more on the periphery or where they do not value customers.


Virtually any car with time requires a greater amount of gasoline per 100 kilometers. It is necessary to undertake repair only when it is economically justified. The high cost of work in this case does not cover the waste of fuel. Therefore, is it worth fighting with extra liters everyone decides for himself.