I cant remember who was asking about this, but here goes. My mileage with the 370's and a heavy right foot average 17. 42 MPG city and hwy mix(50-50). Thats an increase of . 2 MPG. I will be taking a long trip to FLA. in March will and will report highway MPG. Im happy with the increase that the 370's have given me. Plus the powerOo. Oo. .