Last I heard, this Fall, from a neighbor who runs an OTR trucking company, and has an 010 tractor with (I think) a Cat in it, is, that he's spending several hundred bucks a month on urea, alone. Hates his 09 Ford diesel pickup, for the mileage he's getting, VS the power output, too. Sort of harks back to 73~, when we had the mfgs scrambling to meet emmisions, while halving, or worse, the mileage. How much less polution do you get, overall, when you make less smoke, but burn tripple the fuel?