Several factors can cause a Toyota car to use more fuel suddenly:

Dirty or Clogged Air Filter: A dirty air filter restricts airflow to the engine, causing it to work harder and consume more fuel.

Faulty Oxygen Sensor: A malfunctioning oxygen sensor can send incorrect data to the engine's computer, leading to an improper air-fuel mixture and increased fuel consumption.

Worn Spark Plugs: Old or worn-out spark plugs can cause incomplete combustion, which reduces engine efficiency and increases fuel consumption.

Incorrect Tire Pressure: Under-inflated tires create more rolling resistance, making the engine work harder and use more fuel.

Fuel System Issues: Problems like a clogged fuel injector or a failing fuel pump can lead to inefficient fuel delivery, increasing fuel usage.

Poor Driving Habits: Aggressive driving, such as rapid acceleration and braking, can significantly increase fuel consumption.

Excessive Idling: Keeping the engine running while the vehicle is stationary consumes fuel unnecessarily.

Increased Weight: Carrying extra weight or cargo can make the engine work harder, leading to higher fuel consumption.

Aerodynamic Drag: Adding roof racks or driving with windows down can increase aerodynamic drag, reducing fuel efficiency.

Old or Improper Engine Oil: Using the wrong type of old engine oil can reduce engine efficiency and increase fuel consumption.

Faulty Thermostat: A thermostat stuck in the open position can cause the engine to run cooler than optimal, increasing fuel consumption.

Transmission Issues: Transmission problems, such as slipping gears or delayed shifts, can lead to higher fuel usage.

Exhaust System Issues: A leak or blockage in the exhaust system can affect engine performance and fuel efficiency.

Use of Air Conditioning: Running the air conditioner puts additional load on the engine, increasing fuel consumption.

Fuel Quality: Using lower quality or contaminated fuel can lead to poor engine performance and higher fuel consumption.

Regular Maintenance Neglect: Skipping regular maintenance like oil changes, air filter replacements, and engine tune-ups can lead to decreased fuel efficiency.

Addressing these factors can improve your Toyota car's fuel efficiency and reduce fuel consumption.