My '15 Dart Aero got close to 45 mpg on the interstate at 70-80 mph before my dealer did the first tune up just after the warranty ran out at $258.00 and left the emission hose off. They would not allow me to bring it back for a whole week, and since it only gets 25 to 30 mpg around town and maybe 35 on interstate. The airbox is also oily. I am not sure how to get it repaired. I will never trust the dealer again.