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					Originally Posted by joselu43
					
				  But I think that the big picture is that in some cases it may be a good idea to explore changing the gear ratio to improve mileage. In my view, the percentage will depend on the particulars. You may lose or gain.
 JL
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 Exactly right.
There is no disagreement that a reduction in engine speed will improve the fuel economy of a vehicle with a diesel engine.  You definitely will not lose.
The issue is whether or not your percentage gain exactly matches your axle ratio change.  This was his original premise.