Hello all,
New to the forum...happy to be a xfire owner...always wanted one...and yes now I'm a clean freak when it comes to the vehicle....

On topic...I moved onto the xfire after owning a Mercedes...which took premium gas...since I enjoy keeping tabs on the tech aspects of my cars I was a member of mercedesshop forum and this question was a common one...MB engines have knock sensors and other electronics to compensate for lower octane fuel so as to avoid damaging your engine...this also usually ends up decreasing performance (albeit usually unnoticeable) as well as lowering your fuel economy a bit...which often negates any savings you may have incurred...