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Old 11-28-2013, 02:10 AM   #2 (permalink)
NachtRitter
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Join Date: Dec 2008
Location: Placerville, CA
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Helga - '00 Volkswagen Jetta TDI
TEAM VW AUDI Group
Diesel
90 day: 54.39 mpg (US)

Mathilde - '99 Volkswagen Eurovan Camper
90 day: 16.87 mpg (US)
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This tip summarizes the recommendation: The most efficient way to slow down

The wording in the tip is key... the method you choose depends on how quickly you need to stop. If you know you need to stop, and you are approaching at a speed where you know you will need to use the brakes, then you may as well take advantage of DFCO so that you use zero fuel for a short period and you reduce your speed more quickly. But as your manual points out, under a certain RPM, you will begin to use fuel again. The delta between the idle speed and the DFCO rpm cutoff point is pretty small, so in the case of the VX it may not make much difference if you leave it in gear all the way to the stop or if you clutch in again when the RPMs drop below 850.

Of course, the best method from FE point of view would be to take the car out of gear (or push in the clutch) much earlier before the stop (if conditions allow it), so that the need to use the brakes (and therefore the need to use engine braking) is significantly reduced.
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