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Old 10-16-2012, 02:38 AM   #5 (permalink)
some_other_dave
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Notice that the readings are in percentages or PPM (parts per million). And that an engine spinning at 2000 RPM is pushing out 3 times as much exhaust as one spinning at 667 RPM. So the total amount of pollutants emitted is not as lopsided as it looks at first.

And if you consider the pollution caused by drilling, pumping, refining, transporting, etc. the fuel that you burn, it might actually be that the idle RPM has less total emissions than the high RPM condition due to burning less fuel. Depending on a lot of factors, of course!

-soD
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