Rep Power: 0

I have recently bought a 2014 honda civic si, I am having a bit of trouble with gas. It seems that I am getting less gas mileage then I expected. The only major modification that I know about is a K&NŽ - 69 Series TyphoonŽ Aluminum Silver Cold Air Intake System, and I am confused if this is causing my issues. I filled up and got around 200 miles (i put 89 in my gas, the middle one). Any help would be amazing I am clueless since I always heard civic's got great gas mileage.

 
Rep Power: 244

You have an Si with a K engine?

They take premium gas and driving habits play a big role in MPG.

What type of driving city or highway? How many gallons did it take to fill it up after hitting 200 miles?

 
Rep Power: 0

With a K engine? or K&N?

I put premium gas & drive normal

Driving 8 miles of highway per day, Monday - Thursday, rest is city. & I believe I filled up 11.5 g?

 
Rep Power: 244

You said you put 89 the middle one in it.

What does the owners manual tell you to use?

Fill the tank with 91 reset the trip and go on a good highway cruise. See what you get.

You bought a more performance oriented Civic. If you want better MPG get a none Si version.