Worse MPG with K&N drop ins?

Originally Posted by zcar_dad

I have had the K&Ns since I bought the car new. My mileage has remained consitent since after the break-in period. I now have 9950 miles on the car. For highway driving I get 25-27 mpg depending on what my average speed is (between 55- 75 miles per hour). Around town it gets around 20-23 depending on average speed. When driven to work it gets more as more highway miles versus city streets are involved. The above includes having high flow cats and using Royal Purple motor oil.