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Old 05-15-2009, 10:35 AM   #18 (permalink)
PaleMelanesian
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Join Date: Dec 2007
Location: Texas
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PaleCivic (retired) - '96 Honda Civic DX Sedan
90 day: 69.2 mpg (US)

PaleFit - '09 Honda Fit Sport
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Quote:
Incidently, neutral engine-on coasting probably delivers worse FE than engine-on coasting in gear on most modern cars. As mentioned earlier lots of newer cars will go into fuel cut-off when deaccelerating in gear. Go to neutral and you are stuck with engine idle consumption if the engine is on.
That's true during that instant, but when you look at the whole trip, the balance tips the other way. I've tested pulse-and-DFCO against pulse-and-neutral idle and against steady speed driving. The results:

Best: pulse and EOC
Good: pulse and neutral idle glide
Ok: steady speed
Worst: pulse and DFCO

You only want to use DFCO if you're needing to lose speed, like coming up to a red light, or down a mountain. Any other time, it's a net loss in mileage. The drag from engine braking overwhelms the gains from no fuel being used.

My honda does DFCO down to 1200 rpm, and below that it restarts the fuel flow. You can feel a surge when this happens.
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11-mile commute: 100 mpg - - - Tank: 90.2 mpg / 1191 miles

Last edited by PaleMelanesian; 05-15-2009 at 10:40 AM..
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