No I wasn't meaning amazing mpg increases, just saying Schaeffer's has several products that use either natural or "synthetic" esters for cleaning purposes.
Well, as for increases, yeah, I have noted them. Typically my mpg gauge starts at about 33 mpg and by the end of a tank is down below 29. My last tank (1st tank post Neutra) stayed at about 31 for a whole tank. I don't know about this current tank b/c I threw in some more acetone.