What are the reasons for increased car fuel consumption?

[NoraLynn]

Possible reasons include low tire pressure, spark plug carbon buildup, or improper lubrication. Below is relevant information about car fuel consumption: 1. Concept of car fuel consumption: Fuel consumption refers to the fuel economy indicator when a car is traveling at a constant speed on good road conditions. Since constant-speed driving is a basic operating condition for cars on highways, and this type of fuel consumption is easy to measure, it is widely used. 2. Calculation of car fuel consumption: On a specialized test track under specified conditions of humidity, air pressure, and tire pressure, with full load and constant speed (weighed with passengers and trunk loaded with weights), specialized measuring instruments (such as graduated measuring cups and flow meters) are used to cut off the vehicle's original fuel supply system. The fuel in the measuring cup is used to drive the car for several tens or hundreds of meters (excluding fuel consumption during acceleration and without coasting). The round-trip fuel consumption is then divided by two to calculate data such as the constant-speed fuel consumption per 100 kilometers.

[JanelleLee]

I've been driving for decades, and recently my fuel consumption suddenly skyrocketed from 7 liters per 100 kilometers to 11 liters. This made me thoroughly inspect my car: the tire pressure showed only 2.0 bar, significantly lower than the normal 2.4 bar, and the deflated tires increased rolling resistance; the air filter was completely clogged with dust, and it improved a lot after replacing it with a new one; I also reflected on my driving habits—frequent rapid acceleration and hard braking made the engine burn more fuel. Furthermore, the engine oil hadn't been changed for too long, becoming sticky and adding extra burden; the spark plugs had some carbon buildup, and cleaning them helped a bit. If you pay attention to regular maintenance, such as checking tire pressure monthly, replacing the air filter every six months, and driving more steadily, fuel consumption will naturally stabilize. Never ignore small issues that can accumulate into big problems.

[McElijah]

As someone who frequently deals with vehicles, I've found that common causes of increased fuel consumption include faulty oxygen sensors, which mislead the computer into injecting more fuel; worn-out spark plugs leading to incomplete combustion, wasting fuel; and clogged air filters preventing the engine from getting enough air, reducing efficiency. During inspections, I first use tools to scan for error codes or check for fuel leaks; tire pressure 5 PSI below the recommended value can increase fuel consumption by over 10%. I recommend car owners perform regular simple maintenance, such as changing the oil every 5,000 kilometers, to keep the vehicle in good condition and avoid unnecessary consumption. This practical approach saves both money and hassle.

[Erik]

Last month I bought a new car, and the fuel consumption suddenly increased from 6 liters to 9 liters. When I asked the mechanic at the service station, he said it might be because I had too much heavy stuff in the trunk, which increased the load; running the AC at full blast also consumes a lot of fuel; and driving with the windows down on the highway creates more wind resistance, which also wastes fuel. The mechanic also advised me to avoid sudden braking and hard acceleration, suggesting that driving smoothly naturally saves fuel. Now, I'm adopting these habits—adjusting the AC, keeping the windows closed, and moderating the fan speed—and the fuel consumption has gradually decreased. As a new driver, it takes time to learn these tricks.