Why is my car using so much gas all of a sudden?

Owning a car births expenses naturally. From doing routine maintenance to fueling your car costs money. While these are a must, overspending on fuel can be overwhelming, especially if you are working on a tight budget.

If your fuel consumption suddenly skyrockets, it’s crucial you address the issue to avoid spending too much on fuel. You can, however, do this only if you know the root cause. So, if you are among those asking, why is my car using so much gas all of a sudden, then read till the end.

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Why is my car using so much gas all of a sudden?

Many people often ask, why is my car using so much gas? Your vehicle could be consuming gas because you drive a lot. Moreover, the “so much” you are talking about might be what is estimated for your car to consume.

Therefore, if your fuel economy suddenly declines, the right question should be, why is my car using more gas than normal? If your vehicle is using more gas than estimated, it may be due to the use of wrong fluid, poor driving habits, and improper vehicle maintenance.

1. Wrong fluid

Your vehicle uses several fluids and could impact fuel consumption if you use:

Poor quality fuel: If you are wondering why is my car eating up so much gas, poor-quality fuel might be the culprit. Low-quality fuel takes longer to kick start the engine; the longer your vehicle takes to start, the more fuel it consumes. Moreover, bad fuel can also leave residue after burning out, clogging the engine over time.

Poor quality engine oil: Oil comes in different viscosity, and which your car needs is dependent on your vehicle. Poor quality oil doesn’t allow proper lubrication of the engine part.  Because improper lubrication causes parts not to move freely, it puts more stress on the engine, causing it to work harder. The harder your engine works, the more fuel it consumes.

2. Driving habits

Here is how your driving habit can impact fuel consumption negatively:

Driving Short distances: The vehicle uses more fuel at the beginning of a journey since the car is not yet warm. So, if you regularly drive short distances, your vehicle will use more fuel since it never reaches its optimal operating temperature.

Driving in the wrong gear: Every gear has a specific speed they are meant for. If you keep cruising at higher speeds using lower gears, you will consume more fuel than usual.

Not warming the vehicle before driving: A car’s engine takes longer to reach an operating temperature, especially during winter. If you don’t idle for a while, the vehicle will not get warm before you drive. Generally, driving a cold engine increases fuel usage.

Idling for too long: While idling helps warm your car, keeping the car idle for too long drains your fuel. Your vehicle will be stationary, but so long the engine keeps running for long, you will lose gas. So, if you are asking why is my car eating up so much gas? Check how long you’ve been idling recently.

Overloading: Some vehicle owners throw just anything in their boots before starting a journey. However, while this seems very convenient, too much load in your car strains the engine since it has to work harder than usual. The harder the engine works, the more fuel it consumes.

Overspeeding and under-speeding: Generally, driving at speed on highways will usually cost you more fuel since the engine works to overcome wind resistance.

If you, however, choose to lower the speed a bid to save fuel, you’ll end up using more fuel since you will drive longer. Speed when necessary and slow down when necessary.

Accelerating quickly: Accelerating faster causes your engine to work hard, invariably causing your engine to use more fuel. So, if you’re experiencing a drastic increase in fuel consumption, check how fast you’ve been accelerating recently.

Abrupt braking: Like accelerating, hitting the brake suddenly also impacts fuel consumption since the engine works more. This happens more in stop-and-go traffic when you’re too close to another.

Always putting the AC on and not using the AC at all: If your vehicle consumes more fuel than usual, check the rate at which you use your AC. AC increases the load on the engine, so putting it on will make your vehicle consume more fuel. The use of AC is usually rampant in summer.

Similarly, not using the AC at all can also increase gas consumption. When driving at very high speeds with windows down, there is a lot of wind resistance. That surely causes your engine to burn more fuel. So, while you may feel you’re saving fuel, you’re wasting it.

3. Improper maintenance and faulty components

Not doing routine maintenance and driving with bad components is another way your vehicle eats fuel than it should. This includes

Using too old or underinflated tires: Tires keep the vehicle in constant contact with the road.  However, when they get too old or are not correctly inflated, they lose road grip, causing them to spin more to retain a certain speed. This puts more pressure on the engine, invariably causing your vehicle to use more fuel.

Failing clutch: A clutch in poor condition often causes slippage, which is the reduction of contact between the pressure plate and the clutch. In this case, some of the power generated by the engine doesn’t go to the wheel and, therefore, wastes away. This causes more fuel usage.

Using too old or contaminated fluid: The engine oil and other fluids in the vehicle have a specific time they should be changed. Failure to keep up with such maintenance results in the oil losing its viscosity and lubricating power.

Because engine parts aren’t adequately lubricated, they strain the engine and increase fuel consumption. That can impact both gasoline and diesel engines. So, for those asking, why is my car using so much diesel? One is staring at you.

Fuel leakage: Fuel leakage is one of the most common reasons your vehicle uses gas normally. Fuel leaks can arise due to damaged fuel tanks, bad gas caps, damaged fuel lines, and fittings, or other components of the fuel delivery system. Aside from losing fuel, driving with damaged tanks or fuel lines puts you at risk of fire hazards.

Low fluid: Like using old fluid, low engine oil or coolant causes improper lubrication of parts and overheating. This strains the engine, invariably causing excess fuel usage.

Bad oxygen (O2) sensors: The O2 sensors monitor the amount of air in the exhaust and communicate this with the engine computer. With this information, the ECM pushes more or less fuel into the engine.

If, however, the sensor is faulty, it may send a wrong reading and cause the ECU to inject excess fuel into the engine. Moreover, surplus fuel in the engine impedes vehicle performance due to incomplete combustion. So, if you’re looking for what drains gas in a car, here you go.

Faulty fuel injector: The fuel injector is responsible for injecting fuel into the engine. If, however, it gets bad or stuck in the open position, it pushes excess fuel into the engine. This not only costs you more fuel but tampers with the air-fuel ratio.

Incorrect air-fuel ratio causes engine misfires and many other performance issues. For those confused and asking, why am I losing so much gas in my car suddenly? A faulty fuel injector is a possible culprit.

Bad spark plugs: Spark plugs are an essential ignition system component that provides the spark needed to ignite the air-fuel mixture to start the engine.  However, when faulty, they find it challenging to create the spark needed to start the car.

This not only impacts fuel consumption but also results in misfiring. Aside from the plugs, other ignition components, like the ignition switch, coil, etc, might also cause spark issues and increased fuel consumption.

Bad air filter: Bad air filters are one of the reasons for low mileage in petrol cars. Air filters ensure only clean air enters the engine by helping to trap dirt and other contaminants. This action, however, gets it clogged over time, restricting airflow.  When the engine doesn’t get sufficient air, the ECU compensates for lack of air by shoving more fuel into the engine.

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What to do if my car is using so much gas suddenly

If you are among those asking, how can I stop my car from burning so much gas? You may need to explore the following.

Repair or replace faulty parts

Check to see all engine components are working correctly. Thankfully, you can quickly find the real culprit by using an OBD II to scan for error codes. Are the sensors, actuators, and other components working?

Clean dirty sensors and reusable air filters, and replace bad fuel injectors and faulty components. However, if you’re experiencing poor gas mileage with no codes, chances are your engine components and fluids are intact. A possible culprit will be how you drive. Of course, your scanner can not read error codes for that.

Service your car

When last did you service your car? Ensure your tires are properly aligned and inflated according to manufacturer specifications. Also, check if your tires are due for a replacement. Top low fluids and change old ones, ensuring you replace with only those recommended for your car.

Check the fuel you’re using.

Did you change the fuel station recently? It’s almost impossible that a station selling good quality fuel will switch to selling bad ones.

Revaluate your driving habits.

If you have recently been overloading your car, try as much as possible to remove those less important stuff; carry only what you need. Did you suddenly start taking short distances, accelerating too hard, or braking rapidly; stop these.

Check the route you’ve been taking recently; if you have been getting stuck in stop-and-go traffic, it will impact your fuel usage negatively. Plan new routes if possible. Speed when necessary and vice versa, and use gears that tally with your speed.

Important tips to get better mileage

The tips below will help you save on gas whether you’re having a bad mileage or not. But what is considered bad gas mileage? Bad mileage is using gas beyond manufacturer spec.

But the thing is, your car could be using fuel according to manufacturer specifications but still be on the high side. However, whatever category you fall in, following these tips can help improve fuel economy.

Ensure your tires are in good condition.

Healthy and properly inflated tires will ride smoothly and won’t put pressure on the engine to attain a certain speed. So change old or worn tires and keep tire pressure according to manufacturer specification.

Fix bad components

Change bad O2 sensors, spark plugs, injectors, and other components that can impact fuel consumption.

Use only good-quality fuel.

Look out for filling stations that sell only quality fuel. Good fuel not only improves fuel economy but also keeps the engine clean since it contains additives.

Invest in quality oil.

Using oil with the correct viscosity helps with proper lubrication and makes engine parts move freely. This way, your engine doesn’t have to work too hard. If you’re uncertain what oil best suits your car, refer to your owner’s manual.

Always idle for a while

Cultivate letting your car idle so it warms up before you drive.  If you’re waiting or stopping for long, don’t shut and restart the engine.

Stay at your vehicle’s optimal speed.

Driving at 60 MPH generally improves gas mileage. However, if you must go above this, don’t exceed your vehicle’s optimal speed level. More importantly, unless the situation calls for driving at speeds, slow down.

Avoid driving aggressively

Overspeeding, accelerating quickly, and stopping suddenly cause the engine to work harder, invariably leading to high fuel consumption. So, stop driving aggressively.

Don’t idle for too long.

If you are in stop-and-go traffic that has lasted more than 15 seconds, turn off the engine. Do the same when waiting for someone in your car.

Keep vehicle weight light.

Remove things that are not too important from your car. For example, the roof rack can go off. The less load you take in, the less harder your engine works and the less fuel consumption.

Maintain a constant speed.

Changing speed at regular intervals increases fuel usage. For cars with cruise control, activate it so it keeps you at a steady speed. However, only do this on a road where changing gears isn’t needed.

Use AC when necessary.

Drive with your AC on when cruising at high speeds and wind the windows down when on low speed.

Replace old fluid and top low ones.

If your fluids get low or contaminated, top till they reach the correct fill line, or replace them with a fresh one. And do this at the right time. For example, an oil change is recommended every 5,000 to 7,500 miles, depending on the car.

Avoid short stops

If you can, avoid any stop-and-go traffic, as this situation strains the engine and causes you to use more fuel.

Routine maintenance is key.

Lastly, doing routine maintenance helps detect faults in time and eventually prevents overusing fuel.

Final Words

The question, why is my car using so much gas all of a sudden, has been answered.  These include driving with faulty components, wrong or low fluid, and poor driving habits.

To avoid excessive fuel usage, keep up with routine maintenance as that helps to know the condition of various fluid and tract faulty parts on time. Avoid driving short distances, putting too much load in your car, aggressive driving, etc.

Osuagwu Solomon

Osuagwu Solomon is a certified mechanic with over a decade of experience in the mechanic garage, and he has over five years of experience in the writing industry. He started writing automotive articles to share his garage experience with car enthusiasts and armature mechanics. If he is not in the garage fixing challenging mechanical problems, he is writing automotive repair guides, buyer’s guides, and car and tools comparisons.

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