content: OK, first of all this sounds like complete nonsense. However, I know there were some emissions recalls on newer model Buicks, so let's pretend like you were in a mandatory state and some kind of engine work happened. Now we would run into your numbers. There are no Buicks that get 35mpg highway except for ONE model - an e-assist hybrid, and that one just barely. Most of them don't even get 30 highway. Most get from 20-25 in realistic combined driving. So besides the fact that screwing up a highly tuned modern engine to lose 30% of it's mpg rating would necessitate making it run like absolute trash which ruins both performance AND emissions, it's far more likely that there's some "Omg they ruined my mpg!" bias going on here... again assuming this happened. By all means show me some information or proof about this, I'd be glad to see it.