But... if we burn 30-50% less fuel, then wouldn't that balance out the supposed increase in pollution? Wouldn't burning less fuel decrease the so-called "greenhouse" emissions?
I remember the first brand new vehicle I every purchased - a 2000 Dodge Ram 1500 QuadCab with the 360. Was a good truck. But about 6 months after I bought it, there was a recall. Apparently, the computer was tuned in such a way, that emissions were just a hair over regulation. So - after they reprogrammed the computer, not only did the engine make less horsepower (enough you could tell when pulling a load or simple hard acceleration), but I lost nearly 2 mpg in all-around driving. I tried to get the dealer to "undo" the program - but they said it would be illegal.
A member of our previous church bought a brand new Dodge Ram 2500 with the Cummins. Great truck, but got 4mpg LESS than the one it replaced that was just two years older. When he asked the dealer why - they should have been essentially identical - the dealership said that it was due to the new emissions regulations.
I just don't get it... make engines LESS efficient, so the pollute less per gallon of fuel burned...
Although its hard to comprehend that burning less fuel could produce more combustion by products, but the composition of those by products can indeed be more harmful. The higher combustion temperatures create a lot of otherwise less viable NH3, NOX and hydrocarbon compounds.