What Causes a Sudden Increase in Car Fuel Consumption?
3 Answers
The reasons for a sudden increase in car fuel consumption are as follows: 1. Decreased thermal efficiency leads to increased fuel injection: In winter, the vehicle's fuel consumption rises because more heat energy is required, and the engine must work harder to maintain operating temperature. If the winter engine oil has high viscosity and the engine block temperature is low, fuel atomization becomes less effective, causing a significant portion of the fuel to be expelled without full combustion, failing to convert into useful work. To maintain the original output power, the engine inevitably increases fuel injection. 2. Additional engine workload due to cabin heating: In summer, using the air conditioning causes part of the engine's kinetic energy to be lost to the AC compressor, making increased fuel consumption understandable. In winter, heating is unrelated to the AC compressor, but improper methods can also increase fuel consumption. The heat in the cabin comes from the engine, and using the engine's heat for warmth will inevitably cool the engine. Although the engine generates a large amount of residual heat during operation, until the engine temperature rises to the predetermined value, its operating efficiency cannot reach the highest level.
Last time my old car's fuel consumption suddenly soared to 14L/100km, so I specifically went to my trusted repair shop. The master mechanic first had me check the tire pressure - sure enough, the right rear tire was only at 1.8 bar. After inflating it to 2.4 bar, fuel efficiency improved immediately. Then we found the air filter hadn't been changed for six months, clogged like a mask covering the mouth - after replacement, air intake became much smoother. When we removed the spark plugs, the electrodes were completely worn out, so all four were replaced. The most surprising find was the oxygen sensor - though the warning light wasn't on, computer diagnostics showed abnormal readings. A faulty oxygen sensor can make the engine stupidly inject extra fuel. Finally, he reminded me to clear out two cases of mineral water from the trunk, equivalent to carrying an extra child every day. Now fuel consumption has returned to 8.2L/100km. These are all areas everyone should really pay attention to.
As a freight driver with twenty years of experience, I've seen countless cases of sudden fuel consumption spikes. Last month, my apprentice's truck suddenly burned three extra liters per hundred kilometers—turned out the brake caliper was stuck, effectively driving with the brakes engaged. Another time, fuel consumption skyrocketed with the AC on during summer; only after replacing the refrigerant did we realize the compressor bearing had failed, forcing the engine to work 30% harder to turn it. The classic case was Old Wang, who cheaped out on gas from a shady station—the injectors got clogged with deposits, ruining atomization. He had to mix a bottle of fuel additive into every tank to recover. Remember: when fuel consumption acts up, first check wheel hub temperature, then sniff for foul exhaust smells, and finally listen for engine strain. These three tricks can quickly pinpoint the issue.
