You can turn the ALDA clockwise to lower the boost enrichment, but power will drop some as well. I would imagine it would help MPG since its not enriching as much on the highway while in the turbo range.

I'm getting 23 city, 27 highway with a gallon or 2 of filtered motor oil in the tank. I see no difference in smoke / drivability at that concentration. Remember with diesel around $3 a gallon, one gallon drops my fuel price by 20-30 cents per gallon. Last tank I got the equivalent of 28 mpg city by adding roughly a gallon once my tank got down to 3/4 (i fill it to the top at the pump).

__________________
Adam Lumsden
(83) 300D
Vice-President of the MBCA International Stars Section