Why your car is consuming more fuel than it should?

A fuel-efficient vehicle is one of the top priorities for buyers in India. It’s not hard to see why, either: ever-rising fuel costs bring efficiency to the foreground when buying considerations are put forth. To manufacturers’ credit, they have done their bit and stepped up; cars sold in India are getting increasingly more efficient. In 2024, there are a number of vehicles that return in excess of 20 kmpl.

With that said, there are plenty of reported incidents of inherently fuel-efficient vehicles delivering less-than-stellar efficiency figures. There are plenty of good reasons for your car being less efficient over time, and there are plenty of simple and manageable steps that you can take to curb this upward fuel consumption trajectory.

Our guide to understanding why your car consumes more fuel than it should will go through maintenance tips and tricks, and what you can do to help lower it.

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Reasons for increased fuel consumption

There are a number of reasons your vehicle might be consuming more fuel per kilometre. However, it is more than likely that the fault lies with one (or more) of these reasons:

1) Engine performance issues: A vehicle with an engine issue is a serious concern. If the vehicle in question has not broken down yet, an engine that’s not functioning optimally will manifest itself in many ways, with one of the most telling being that the fuel efficiency will drop significantly. Even if you don’t have the expertise to do it yourself, it is always advisable to have the engine’s essential components (spark/glow plugs, oxygen sensors, fuel injectors, valves, pistons, etc.) regularly checked by a trusted mechanic. An engine plays a crucial role in converting fuel to motive power and naturally has a lot of components that require optimal functioning to complete the combustion process as intended.

2) Incorrect engine oil selection: Your engine’s components need constant and proper lubrication to perform at their optimal levels. In that sense, ensuring your car gets the correct engine oil is crucial. It is always advisable to pick the correct grade of oil that your engine needs to keep it running smoothly. If an incorrect grade of engine oil is used, there’s a very high possibility that not just your fuel consumption will increase, but also that your engine’s components risk being damaged. For the best results, always stick to the grade of engine oil the manufacturer recommends for your vehicle.

3) Bad fuel quality: Ensuring your vehicle gets clean, additive-free fuel is more important than most people think. Keep in mind that the kind of fuel you put in your car is the only thing that makes it function properly, so only fill it with petrol pumps that are trustworthy and reliable. Certain pumps will try to sell you fuel additives that they claim will help with your vehicle’s fuel consumption, but this should be taken with a pinch of salt. While some additives certainly help, many can cause irreversible damage in the long run. In this instance, it’s best to take the advice of a trusted mechanic if you are uncertain yourself.

4) Improper maintenance and short round-trips: If your vehicle is not regularly maintained and cleaned, there is a very high likelihood of your fuel consumption increasing. Here, we mean the maintenance and cleanliness of crucial engine (and other) components. For instance, a clogged fuel line means that either not enough fuel is reaching the engine or impure fuel is being used. This could lead to increased levels of fuel being delivered or, in a more extreme case, eventual damage to the engine’s components. Needless to say, neither scenario is ideal. Additionally, frequent short trips, such as those less than 5 km, do not allow the engine to reach its optimal operating temperature, leading to higher fuel usage. Regular maintenance, replacing old tyres, oil changes, and tune-ups can help improve engine performance and mileage.

Additionally, a worn clutch is a factor that can lead to decreased fuel efficiency. As the clutch ages, it results in a loss of power transfer from the engine to the wheels, reducing transmission efficiency and increasing fuel consumption. Hence, regularly having your clutch checked and replaced can decrease the wear and tear and increase the mileage of your car.

5) Improper driving techniques: More often than not, how you drive your car is the biggest reason your car delivers the kind of fuel efficiency it does. This is an aspect that’s often overlooked by most but is one of the simplest and most effective measures you can adopt to help increase your vehicle’s fuel efficiency. To that effect, anticipating your next gear shift (in the case of manual transmission-equipped vehicles), avoiding sudden braking and accelerating, lifting and coasting, and driving at a measured pace at all times can help increase fuel consumption, especially in busy traffic conditions. Another great exercise to follow is switching your vehicle off at a traffic light when you know that you will be stationary for more than a minute will go a long way.

6) Excessive use of the air conditioner: Excessively using the AC contributes to higher fuel consumption in your car. The AC unit drains power from the engine, leading to increased pressure on the engine and greater fuel consumption. Until the temperature is tolerable, it's advisable to keep the windows open to avoid decreased fuel efficiency. However, if driving at high speeds, opening the windows increases drag and puts additional strain on the engine, which means the AC will not significantly impact fuel consumption.

7) Under-inflated tyres: Under-inflated tyres increase the contact patch, which increases the amount of drag that the car has to overcome. This means that the engine is under more load than usual. This translates to more fuel being consumed to move the vehicle. It’s always advisable to keep your tyre pressures regularly checked and maintain the recommended tyre pressures.

Petrol cars in India with the best mileage

Today, there are quite a few petrol cars on sale in India that come with impressive fuel economy figures. Understandably, they’re all compact vehicles with small-displacement engines and low kerb weights, all factors that help in increasing fuel efficiency.

Fuel system problems affecting efficiency

The fuel system in any vehicle is one of the most critical components of the engine. Consequently, any issue that the fuel system runs into will mean that the engine won’t run optimally. Sub-optimal engine performance can manifest itself in many ways, but one of the key ways is a drastic reduction in fuel efficiency. The issues with fuel systems generally boil down to two factors:

1) Fuel injector issues: This is one of the most common fuel system issues. Typically, what happens is that the fuel injectors pump a steady and predetermined line of fuel. If an injector cannot open, the engine may end up losing power. Alternatively, an injector that won’t close can cause a serious leak. The good news is that identifying a fuel injector issue is quite simple. The most common symptoms of faulty fuel injectors include issues when cranking the engine, fluctuating engine revs, or simply rough running conditions. There is also a very high chance of fuel efficiency increasing significantly. At this point, it is ideal to consult a trusted mechanic to help rectify the issue.

2) Faulty fuel pumps: Another common issue that leads to increased fuel consumption is a faulty fuel pump. Fuel provides lubrication and cooling for the pump. If you constantly run your vehicle with low fuel, it can eventually lead to a fuel pump drying out or overheating, and potentially even failing. It could also be caused by loose or worn connections when the pump doesn’t receive the right current flow. A fuel pump malfunction has mostly the same symptoms as a fuel injector issue: engine cranking difficulty, irregular engine idling, and unpredictable acceleration. Just like the fuel injector issue, a fuel pump is ideally best left to a trusted mechanic to diagnose.

Impact of weight and load on fuel consumption

Fuel efficiency for a vehicle is a factor that’s dependent on a lot of variables. Aside from the issues we already addressed, the amount of load you put on a vehicle also has a direct effect on fuel consumption. To that effect, the following are two factors you should keep in mind at all times:

1) Excessive cargo: Loading your car with a lot of weight increases the strain on your engine. An increased amount of strain on your engine means that more fuel is being consumed to cover a similar distance, which leads to a drop in fuel efficiency. While loading your car up with luggage occasionally is perfectly acceptable, you should remember to stay within the limits prescribed by the manufacturer. In the vehicle’s manual, there will be a suggested maximum load capacity, and staying within that limit will allow you to maintain your efficiency figures.

2) Roof racks and accessories: Certain cars have load-carrying roof racks that can theoretically increase the amount of storage space available in your car. That said, the luggage on the roof racks not only weighs down the car more, it also increases drag. Both lead to a significant increase in fuel consumption.

Maintenance tips to improve fuel efficiency

A vehicle with a high fuel efficiency figure is high up on the list of priorities for most car buyers in India. Step one is to select a vehicle that comes with a high, ARAI-tested fuel efficiency figure. The next step is following a few pointers yourself that could help improve fuel efficiency. 

1) Regular engine checkups: Ensuring your car’s engine components are all functional is crucial if you want good fuel efficiency. While it is always a good idea to keep an eye (and an ear or two) out for troubling signs from your vehicle, it’s recommended that you regularly get your engine checked. This can be done during the scheduled services or simply whenever you feel there’s the potential for an issue down the line.

2) Tyre pressure monitoring: Keeping your tyres well inflated is an important aspect of improving/maintaining your car’s fuel efficiency. It should be noted here that over- or under-inflating tyres also negatively affects fuel consumption. Always stick to what the manufacturer has recommended pressures for the vehicle based on the amount of load being carried.

3) Changing oil and filters: A car’s fuel efficiency is easy to maintain as long as the fluid levels and filters are constantly monitored and replaced at recommended intervals. Keep track of your car’s running, and make sure that engine and transmission oils and air filters are swapped out periodically. 

Conclusion

A fuel-efficient vehicle is, understandably, one of the biggest priorities for Indian car buyers. That said, keeping your car fuel efficient through its life requires a degree of maintenance and discipline on the part of the owner of the vehicle. There are various components that affect a car’s fuel efficiency, and keeping track of all of them constantly should be a priority.

That said, far from being overwhelming, it should be noted that as long as your car is regularly serviced, well inspected and maintained, and driven responsibly, it is easy to extract a respectable efficiency figure month after month.

FAQs

Q. Why is my car suddenly using more fuel?

A number of factors come together to affect a car’s efficiency figure. If your fuel consumption has gone up but your commute and driving habits are the same, it’s best to get your car scheduled for a thorough service to get the problem diagnosed by a trusted mechanic.

Q. How to fix high fuel consumption?

High fuel consumption could be a symptom of certain engine components or the fuel system being faulty, so it’s best to get it checked immediately. It could also be because of improper driving habits.

Q. Why is my fuel running out so quickly?

If your driving habits haven’t changed, then your vehicle is probably consuming more fuel than normal because of excessive load, a fault in some engine component, or the fuel system needs to be checked.

Q. What causes high fuel consumption in petrol engines?

A number of factors could lead to high fuel consumption. These include excessive load, improper driving habits, or a fault with the engine or fuel supply system.