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Old 02-28-2020, 09:49 AM   #1 (permalink)
MetroMPG
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Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
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Blackfly - '98 Geo Metro
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Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 53.56 mpg (US)

Winter beater Metro - '00 Chevrolet Metro
90 day: 61.98 mpg (US)

Fancy Metro - '14 Mitsubishi Mirage top spec
90 day: 58.72 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
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CVT's (non-hybrid) = fewer opportunities for fuel-cut mode (DFCO) when coasting?



The last CVT I spent much time driving was the 1.2L, 3-cylinder Mirage pictured above.

I was genuinely impressed by how much it was programmed to pursue fuel economy: It tries its little heart out to keep cruising revs as low as possible (see chart).

I remembered being pleasantly surprised that...

Quote:
On level roads with a light foot, you can drive around all day at sub/urban speeds under 1500 RPM, including during light acceleration.
That has me wondering: do CVT's programmed for such low RPM, fuel-saving operation offer fewer chances for zero fuel burn (DFCO) when releasing the throttle and coasting in gear? Seems possible you might only get a brief fuel cut before injection resumed to keep the engine running.

Other types of transmissions would have the engine at a higher RPM for a given road speed at the start of coasting. So, more time in fuel cut-off mode.

If that's the case, a CVT hypermiler might benefit from more neutral coasting.

Splitting hairs? Probably! These are the things that keep me awake at night.

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Mitsu mods: Oops, I did it again! Bought another cheap, 3-cylinder Mirage. Mods in progress...
Ecodriving test: Manual vs. automatic transmission MPG showdown



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