Save $855 or 5700 free miles per year.... If you get 5 MPG better with Aero and your tank holds 11 gallons and you fill up twice a week, my math brings approximately 5700 free miles per year. That's 285 free gallons a year based on an average of 20 MPG 285 x $3 = $855 that will pay for alot more than just the AERO Muffler