Clemency also has a cast time so you can ' t open with that . <| sep |> So tired of these journalists just tweeting bullshit to get followers . And then they ' re called out for being wrong but nothing happens . All you can do is say that guys full of shit but in the end that pretty much has no effect on them . <| sep |> They there is something wrong with your car ' s readings or you ' re seeing something that isn ' t there . Most gas stations in a given area will be served by the same refinery , and therefore the same gasoline . The only thing I can think of is that gasoline with 10 % Ethyl Alcohol added may have a slight MPG difference because of its slightly lower energy density . But 67 MPG is quite a whopping difference and I don ' t think this would explain it , and I think that most gasolines typically include E 10 .