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Old 10-20-2009, 10:03 PM   #4 (permalink)
Renaissance Man
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Join Date: Jan 2008
Location: In the Northeast dreaming of the Southwest
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Aegean C - '17 Honda Civic LX
90 day: 41.77 mpg (US)
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There is such a thing as Isaac described, I heard it called "adaptive shift profiling" on a Mitsubishi Lancer once. Not sure how many cars have this feature.

As to when the car shifts, it is determined by engine load and RPM rather than vehicle speed. And for your ideal cruising speed, experiment and find out what the slowest speed you can get the torque converter to lock with the tranny in top gear is. It's usually around 35-40 mph. My Escort has trouble keeping the TC locked below 37 mph for example. If you are unsure whether your TC is locked or unlocked, get a reference by driving the car at, say, 60 mph on a level road and note the RPM once it has dropped as low as it will go. Than figure what that would translate to at 45 mph, 40 mph, 35 mph and see if it can achieve that RPM at those speeds. If the RPM is higher than what you calculated the TC is unlocked.

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