What is the reason for the high fuel consumption of old cars?

The increase in fuel consumption needs to be checked. 1. The spark plug gap, ignition coil and cylinder pipeline must be checked for leaks. Too much carbon deposition in the throttle will also have an impact. Also, the front and rear oxygen sensors themselves are dirty or damaged, and the three-way catalytic blockage will also affect the clutch slipping. These are all problems that will affect fuel consumption and driving jitter. 2. If the fuel consumption increases, the power will also decrease, increasing unnecessary expenses. Just find a repair shop or 4s shop to check the items summarized above for maintenance, and the fuel consumption will be reduced. 3. At present, the oil price is also good. It is normal to consume about 6.5-7 gross per kilometer.