Why does the old Changan Mazda 3 consume more fuel?

[StCassidy]

The old Changan Mazda 3 consumes more fuel mainly due to excessive engine carbon deposits. Here are the measures to solve the high fuel consumption: 1. Clean engine carbon deposits: Excessive engine carbon deposits are a significant cause, primarily due to the use of unsuitable fuel. It is recommended to add a certain amount of cleaning agent when refueling, and after cleaning, it is best to drive at high speed for a while, which helps increase exhaust volume and allows stronger airflow to remove larger carbon deposit particles. 2. Check the oxygen sensor: As an internal control unit of the car, the oxygen sensor mainly monitors the fuel-air ratio of the engine. Once it is damaged, it will cause an imbalance in the fuel-air ratio, and fuel consumption will definitely increase suddenly. After the oxygen sensor is damaged, the exhaust pipe will emit darker-colored exhaust gas during driving, and the oxygen sensor should be replaced at this time. 3. Regularly replace the three filters: During vehicle use, the oil filter, air filter, and fuel filter must be replaced regularly. If they are not replaced for a long time, they will become dirty and affect performance, sending incorrect information to the engine control unit, resulting in incomplete fuel combustion and increased engine carbon deposits.

[AlexandraDella]

I've been driving an old Mazda 3 for over a decade and found that the high fuel consumption is mainly related to the vehicle's age. This car uses the older MZR engine, whose technology is less efficient compared to modern cars, especially the 4AT transmission in the automatic version—it always runs at higher RPMs during highway cruising than newer models. In city driving with frequent stops and starts, the fuel consumption is particularly high. Around the eighth year of ownership, I noticed a significant increase in fuel consumption, which turned out to be due to severe carbon buildup and worn-out spark plugs. Replacing these parts immediately improved the situation. Low tire pressure is also noticeably impactful, making the car feel like it's driving through mud. For older car owners, I recommend regular throttle body cleaning, replacing spark plugs every 50,000 kilometers, and adopting a habit of gentle acceleration.

[StAlana]

High fuel consumption in older Mazda3 models is quite common, with the core issue lying in powertrain matching. Back then, this car emphasized sporty performance, with engine tuning favoring high-speed performance, resulting in lower efficiency at low city-driving RPMs. Especially for automatic transmission versions, the 4-speed gearbox is inadequate by today's standards - it revs over 2,000 RPM at just 60 km/h. My neighbor's car had a faulty oxygen sensor that wasn't replaced promptly, adding 2 liters per 100 km. Wider aftermarket tires also increase consumption, as the original tires were more economical. These older cars have relatively simple electronic systems - issues like clogged fuel injectors won't trigger fault codes, leading to unnoticed fuel wastage. I recommend focusing on inspecting the intake system and catalytic converter condition.

[Evans]

High fuel consumption in the Mazda3 often stems from daily maintenance issues. With my manual transmission car, I noticed that a dirty air filter makes the throttle noticeably heavier and increases fuel usage. When the fuel injectors get carbon buildup, the atomization suffers, wasting fuel. Not replacing spark plugs at 50,000 kilometers leads to lower ignition efficiency and higher consumption. Pay close attention to these three components and clean carbon deposits regularly. Also, avoid overly thick engine oil—5W30 is ideal, as higher viscosity increases engine resistance. Check tire pressure monthly, as underinflation causes deformation and excessive fuel use. Clear out unnecessary items in the car; traveling light saves fuel too.