Quote:
Originally Posted by Christ
My strongest complaint against the way the EPA monitors emissions is that it's based on emissions per volume, instead of emissions per mile.
Presumably, most people don't let their car idle through an entire tank of fuel, and further, they're more than likely going to be driving at least for the heavy majority of their fuel use... ergo, it makes more sense to determine a vehicle's emissions per mile figure, rather than strictly monitoring it's emissions under no load while idling and revving in a closed environment.
Further to that, while I do understand that the particular focus in on very few emissions types, I do /not/ understand why it's acceptable to waste fuel in order to reduce certain types of emissions... this just increases the other levels of emissions as well as overall consumption, part of what's helping to increase prices on fuel at the pump.
Fundamentally, fuel economy should always be the first and foremost among the battles. The less fuel you are using, the less emissions you have [although some levels of certain emissions may be higher than a vehicle using more fuel]. This, to me, says that we're going about the emissions battle incorrectly... cars that clearly are /capable/ of achieving 30-35 MPG are currently getting 20's... the difference between the two sets of mileage numbers, I'm sure would offset any additional emissions over the course of distance traveled, whereas at least part of the reason for the vehicle to currently get less than optimal mileage is because the test system is based on emissions per volume of spent exhaust, regardless of how far the vehicle might have traveled to produce that volume.
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The way the spot checks are done is by volume or parts per volume. This is only to infer compliance. The actual regulations and tests are by grams per mile (g/mi). The ability to run a full FTP 75 on every car is unreasonable at a user level. Here is a link to the EPA requirements for light duty vehicles.
Light-Duty Vehicle, Light-Duty Truck, and Medium-Duty Passenger Vehicle Tier 2 -- Exhaust Emission Standards and Implementation Schedule | Emission Standards Reference Guide | US EPA
Heavy duty vehicles are based on emissions per mile per horsepower.
And blaming the EPA for technical flubs is pointing fingers at the wrong party. The EPA only sets the standards and the manufacturers are the ones to meet those standards. How they go about it is up to the individual manufacturers. As I have mentioned, emissions tech is improving. Some gasoline engines run so clean their tailpipe output is often cleaner than the intake air. Diesel engines will get there soon enough.