I have a 2012 Corolla XLi. Recently, my car's fuel average suddenly dropped. Previously, on long routes at a speed of around 100-110 km/h, it used to give an average of 16 km/l, but in the last few days, the average has dropped. As soon as the RPM crosses 2, the average starts to decrease. Along with this, the engine sound seems slightly louder, almost like there's a leak somewhere, and there's a slight vibration in the car's pickup.
I've already had the car tuned, replaced the spark plugs, cleaned the throttle body, and used Liqui Moly injector cleaner, but there's still no improvement. I've also had the car calibrated with a scanner. The car has a mileage of 110,000 km.
Please advise
