Over the past month and a half, when driving on the freeway between 65-75MPH, I have noticed that my engine sounds as if it is running higher than normal, but my RPM is still around 2K in 8th gear. Consequently, I have also noticed that my MPG is taking longer than usual to reach 30+MPG, and I am only seeing my MPG hit 31-33 numbers.

I have not changed my driving habits and I have done everything I could think of to remedy this problem. Swapped engine air filters, checked tire pressure, etc., and no luck.

My car is a 2.4 Tech and has almost 151,000 miles on it so I am thinking that MAY be a factor, but I'm unsure. Just hoping it doesn't turn out to be something overly expensive that would have to be fixed.

Has anyone else noticed similar anomalies with their car?