Quote:
Originally Posted by baloo
VW's estimates were right, it's the EPA that is off, and the problem is their testing procedure. The test loop doesn't really include certain scenarios (or at least doesn't give them enough weight) that occur in the real world and that have a very negative effect on a gassers mileage (such as cold starts and extensive idling). < AND especially whack HYBRIDS>
Instead of changing the test loop to reflect real world conditions they try to appropriate this negative effect and apply a "fudge factor" to the test results.
The mileage of a diesel car on the other hand is not affected a whole lot by cold starts and idling, so if you hit them with the same "fudge factor" you get unrealistically low mileage figures. This is exactly what is happening here, and this is also why diesel cars get much better than sticker mileage.
The whole concept of a "fudge factor" is a travesty if you're trying to rate vastly different engine types.
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Its actually somewhat worse than that.
With no real explanation, they went ahead and fudge factored diesels down knowing that that would increase the already negative misrepresentation of their mileage.
They literally decided to increase the error.
Hey, its all for a good cause .
Obviously battery hybrids need all the help they can get since they're basically untenable in the real world - when you look at the whole picture and not just part.
Also, its not so much about the actual test loop results - its mostly about shaving the numbers mathematically on paper.
Roughly, 25% of the error is test driven and 75% is the other.
The Fix is in.
No other nation has this size ratio anomaly between gassers and hybrids on one hand, and diesels on the other in terms of real world data and 'estimated' mileage.