I use a Toyota highlander 2003 model, The RPM is moved higher than normal to attain good car speed. What seems to be the problem? It wasn't so formally. Preciously, with steady 2000 RPM the car speed can get up to 80km/hr. But now the RPM exceeds 3000 to attain a speed of 80km/hr. And its gets worse when trying to attain a higher speed. Please advise on how to solve this problem. Thank you.
If I assume that this is a manual transmission, then what you describe is classic symptoms of the clutch slipping. This means that either the friction plate is excessively worn or the pressure plate is weak.
If it is an automatic transmission, then it may be due to low fluid, which may well lead to more serious problems.
Either way this will need to be checked and corrected.